FWU: Remove image_id arg from FWU_SMC_IMAGE_RESUME ...

The current implementation of FWU_SMC_IMAGE_RESUME when called
from the normal world, uses the provided image_id argument to
determine which secure image to resume into. This implies that
the normal world has a choice of which secure image to resume
into when in fact it is only possible to resume into the
previously interrupted secure image.

This patch removes the argument, tightens up the pre-conditions
for the SMC and adds additional asserts.

The pre-conditions for FWU_SMC_SEC_IMAGE_DONE are also
tightened up.

Change-Id: Ia5a46753bb01e8f8dad8a2999314f90db8f300e8

FWU: Fix secure memory check in image auth ...

The implementation of FWU_SMC_IMAGE_AUTH performs a number of
pre-condition checks before authenticating the image. One of
these checks calls `bl1_plat_mem_check()` to ensure the image
source is mapped in when authenticating an image in place.
The framework incorrectly passes the security state of the
caller into this function instead of the security state of
the source image.

This patch corrects the defect. The defect would only
manifest itself for secure world callers authenticating
non-secure images in place, which is not done by current
upstream platforms.

Change-Id: I617c7b43e02ac7149f266aeaf3874316e62f3003

FWU: Add Generic Firmware Update framework support in BL1 ...

Firmware update(a.k.a FWU) feature is part of the TBB architecture.
BL1 is responsible for carrying out the FWU process if platform
specific code detects that it is needed.

This patch adds support for FWU feature support in BL1 which is
included by enabling `TRUSTED_BOARD_BOOT` compile time flag.

This patch adds bl1_fwu.c which contains all the core operations
of FWU, which are; SMC handler, image copy, authentication, execution
and resumption. It also adds bl1.h introducing #defines for all
BL1 SMCs.

Following platform porting functions are introduced:

int bl1_plat_mem_check(uintptr_t mem_base, unsigned int mem_size,
unsigned int flags);
	This function can be used to add platform specific memory checks
	for the provided base/size for the given security state.
	The weak definition will invoke `assert()` and return -ENOMEM.

__dead2 void bl1_plat_fwu_done(void *cookie, void *reserved);
	This function can be used to initiate platform specific procedure
	to mark completion of the FWU process.
	The weak definition waits forever calling `wfi()`.

plat_bl1_common.c contains weak definitions for above functions.

FWU process starts when platform detects it and return the image_id
other than BL2_IMAGE_ID by using `bl1_plat_get_next_image_id()` in
`bl1_main()`.

NOTE: User MUST provide platform specific real definition for
bl1_plat_mem_check() in order to use it for Firmware update.

Change-Id: Ice189a0885d9722d9e1dd03f76cac1aceb0e25ed