Add Firmware Image Package (FIP) driver ...

The Firmware Image Package (FIP) driver allows for data to be loaded
from a FIP on platform storage. The FVP supports loading bootloader
images from a FIP located in NOR FLASH.

The implemented FVP policy states that bootloader images will be
loaded from a FIP in NOR FLASH if available and fall back to loading
individual images from semi-hosting.

NOTE:
- BL3-3(e.g. UEFI) is loaded into DRAM and needs to be configured
  to run from the BL33_BASE address. This is currently set to
  DRAM_BASE+128MB for the FVP.

Change-Id: I2e4821748e3376b5f9e467cf3ec09509e43579a0

Implement load_image in terms of IO abstraction ...

The modified implementation uses the IO abstraction rather than
making direct semi-hosting calls.  The semi-hosting driver is now
registered for the FVP platform during initialisation of each boot
stage where it is used.  Additionally, the FVP platform includes a
straightforward implementation of 'plat_get_image_source' which
provides a generic means for the 'load_image' function to determine
how to access the image data.

Change-Id: Ia34457b471dbee990c7b3c79de7aee4ceea51aa6

fvp: rename fvp_* files to plat_* ...

The FVP platform has a few filenames that begin with fvp_.  These are
renamed to plat_ to make it easier to use the FVP port as a template.

Change-Id: I601e6256d5ef3bae81a2e1f5df6de56db5b27069
Signed-off-by: Ryan Harkin <ryan.harkin@linaro.org>

Build system: minor spacing tidyup ...

Tidy up the spacing of variable definitions within the makefiles to make
them more consistent, easier to read and amend.

Change-Id: Ic6d7c8489ca4330824abb5cd1ead8f1d449d1a85
Signed-off-by: Ryan Harkin <ryan.harkin@linaro.org>

Build system: Fixes #2: Add multi-platform support ...

Move all explicit platform or architecture specific references
into a new platform.mk file that is defined for each platform.

Change-Id: I9d6320d1ba957e0cc8d9b316b3578132331fa428
Signed-off-by: Ryan Harkin <ryan.harkin@linaro.org>