Sanitise includes across codebase ...

Enforce full include path for includes. Deprecate old paths.

The following folders inside include/lib have been left unchanged:

- include/lib/cpus/${ARCH}
- include/lib/el3_runtime/${ARCH}

The reason for this change is that having a global namespace for
includes isn't a good idea. It defeats one of the advantages of having
folders and it introduces problems that are sometimes subtle (because
you may not know the header you are actually including if there are two
of them).

For example, this patch had to be created because two headers were
called the same way: e0ea0928d5b7 ("Fix gpio includes of mt8173 platform
to avoid collision."). More recently, this patch has had similar
problems: 46f9b2c3a282 ("drivers: add tzc380 support").

This problem was introduced in commit 4ecca33988b9 ("Move include and
source files to logical locations"). At that time, there weren't too
many headers so it wasn't a real issue. However, time has shown that
this creates problems.

Platforms that want to preserve the way they include headers may add the
removed paths to PLAT_INCLUDES, but this is discouraged.

Change-Id: I39dc53ed98f9e297a5966e723d1936d6ccf2fc8f
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Standardise header guards across codebase ...

All identifiers, regardless of use, that start with two underscores are
reserved. This means they can't be used in header guards.

The style that this project is now to use the full name of the file in
capital letters followed by 'H'. For example, for a file called
"uart_example.h", the header guard is UART_EXAMPLE_H.

The exceptions are files that are imported from other projects:

- CryptoCell driver
- dt-bindings folders
- zlib headers

Change-Id: I50561bf6c88b491ec440d0c8385c74650f3c106e
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Add new function-pointer-based console API ...

This patch overhauls the console API to allow for multiple console
instances of different drivers that are active at the same time. Instead
of binding to well-known function names (like console_core_init),
consoles now provide a register function (e.g. console_16550_register())
that will hook them into the list of active consoles. All console
operations will be dispatched to all consoles currently in the list.

The new API will be selected by the build-time option MULTI_CONSOLE_API,
which defaults to ${ERROR_DEPRECATED} for now. The old console API code
will be retained to stay backwards-compatible to older platforms, but
should no longer be used for any newly added platforms and can hopefully
be removed at some point in the future.

The new console API is intended to be used for both normal (bootup) and
crash use cases, freeing platforms of the need to set up the crash
console separately. Consoles can be individually configured to be active
active at boot (until first handoff to EL2), at runtime (after first
handoff to EL2), and/or after a crash. Console drivers should set a sane
default upon registration that can be overridden with the
console_set_scope() call. Code to hook up the crash reporting mechanism
to this framework will be added with a later patch.

This patch only affects AArch64, but the new API could easily be ported
to AArch32 as well if desired.

Change-Id: I35c5aa2cb3f719cfddd15565eb13c7cde4162549
Signed-off-by: Julius Werner <jwerner@chromium.org>