Add workarounds for selected Cortex-A57 r0p0 and Juno errata ...

This patch ensures that workarounds for:

1. Erratas #806969 & #813420 that affect Cortex-A57 r0p0 as described in the
   errata notice document

2. Defect id 831273 which affects the Juno platform by triggering the event
   stream every 65536 cycles

are implemented after every reset on each cpu.

Change-Id: I729f608796536704aa956b715bbad428cc854d34

Add initial support for Juno platform ...

Change-Id: Ib3d92df3af53820cfbb2977582ed0d7abf6ef893

Access system registers directly in assembler ...

Instead of using the system register helper functions to read
or write system registers, assembler coded functions should
use MRS/MSR instructions. This results in faster and more
compact code.

This change replaces all usage of the helper functions with
direct register accesses.

Change-Id: I791d5f11f257010bb3e6a72c6c5ab8779f1982b3

Correct usage of data and instruction barriers ...

The current code does not always use data and instruction
barriers as required by the architecture and frequently uses
barriers excessively due to their inclusion in all of the
write_*() helper functions.

Barriers should be used explicitly in assembler or C code
when modifying processor state that requires the barriers in
order to enable review of correctness of the code.

This patch removes the barriers from the helper functions and
introduces them as necessary elsewhere in the code.

PORTING NOTE: check any port of Trusted Firmware for use of
system register helper functions for reliance on the previous
barrier behaviour and add explicit barriers as necessary.

Fixes ARM-software/tf-issues#92

Change-Id: Ie63e187404ff10e0bdcb39292dd9066cb84c53bf

Move include and source files to logical locations ...

Move almost all system include files to a logical sub-directory
under ./include. The only remaining system include directories
not under ./include are specific to the platform. Move the
corresponding source files to match the include directory
structure.

Also remove pm.h as it is no longer used.

Change-Id: Ie5ea6368ec5fad459f3e8a802ad129135527f0b3