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>

Previously the errata reporting was optional for CPU operation
files and this was achieved by making use of weak reference to
resolve to 0 if the symbol is not defined. This is error prone
when adding new CPU operation files and weak references are
problematic when fixing up dynamic relocations. Hence this patch
removes the weak reference and makes it mandatory for the CPU
operation files to define the errata reporting function.

Change-Id: I8af192e19b85b7cd8c7579e52f8f05a4294e5396
Signed-off-by: Soby Mathew <soby.mathew@arm.com>

Change-Id: I2c4b06423fcd96af9351b88a5e2818059f981f1b
Signed-off-by: Joel Hutton <Joel.Hutton@Arm.com>
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>