libc: Use printf and snprintf across codebase ...

tf_printf and tf_snprintf are now called printf and snprintf, so the
code needs to be updated.

Change-Id: Iffeee97afcd6328c4c2d30830d4923b964682d71
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Clean usage of void pointers to access symbols ...

Void pointers have been used to access linker symbols, by declaring an
extern pointer, then taking the address of it. This limits symbols
values to aligned pointer values. To remove this restriction an
IMPORT_SYM macro has been introduced, which declares it as a char
pointer and casts it to the required type.

Change-Id: I89877fc3b13ed311817bb8ba79d4872b89bfd3b0
Signed-off-by: Joel Hutton <Joel.Hutton@Arm.com>

Use SPDX license identifiers ...

To make software license auditing simpler, use SPDX[0] license
identifiers instead of duplicating the license text in every file.

NOTE: Files that have been imported by FreeBSD have not been modified.

[0]: https://spdx.org/

Change-Id: I80a00e1f641b8cc075ca5a95b10607ed9ed8761a
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>

Add Performance Measurement Framework(PMF) ...

This patch adds Performance Measurement Framework(PMF) in the
ARM Trusted Firmware. PMF is implemented as a library and the
SMC interface is provided through ARM SiP service.

The PMF provides capturing, storing, dumping and retrieving the
time-stamps, by enabling the development of services by different
providers, that can be easily integrated into ARM Trusted Firmware.
The PMF capture and retrieval APIs can also do appropriate cache
maintenance operations to the timestamp memory when the caller
indicates so.

`pmf_main.c` consists of core functions that implement service
registration, initialization, storing, dumping and retrieving
the time-stamp.
`pmf_smc.c` consists SMC handling for registered PMF services.
`pmf.h` consists of the macros that can be used by the PMF service
providers to register service and declare time-stamp functions.
`pmf_helpers.h` consists of internal macros that are used by `pmf.h`

By default this feature is disabled in the ARM trusted firmware.
To enable it set the boolean flag `ENABLE_PMF` to 1.

NOTE: The caller is responsible for specifying the appropriate cache
maintenance flags and for acquiring/releasing appropriate locks
before/after capturing/retrieving the time-stamps.

Change-Id: Ib45219ac07c2a81b9726ef6bd9c190cc55e81854