AArch32: Common changes needed for BL1/BL2

This patch adds common changes to support AArch32 state in
BL1 and BL2. Following are the changes:

* Added functions for disabling MMU from Secure state.
* Added AArch32 specific SMC function.
* Added semihosting support.
* Added reporting of unhandled exceptions.
* Added uniprocessor stack support.
* Added `el3_entrypoint_common` macro that can be
  shared by BL1 and BL32 (SP_MIN) BL stages. The
  `el3_entrypoint_common` is similar to the AArch64
  counterpart with the main difference in the assembly
  instructions and the registers that are relevant to
  AArch32 execution state.
* Enabled `LOAD_IMAGE_V2` flag in Makefile for
  `ARCH=aarch32` and added check to make sure that
  platform has not overridden to disable it.

Change-Id: I33c6d8dfefb2e5d142fdfd06a0f4a7332962e1a3
diff --git a/Makefile b/Makefile
index 376db8d..15b1ac8 100644
--- a/Makefile
+++ b/Makefile
@@ -188,6 +188,10 @@
         FWU_FIP_DEPS += fwu_certificates
 endif
 
+# For AArch32, enable new version of image loading.
+ifeq (${ARCH},aarch32)
+        LOAD_IMAGE_V2	:=	1
+endif
 
 ################################################################################
 # Toolchain
@@ -364,6 +368,14 @@
         endif
 endif
 
+# For AArch32, LOAD_IMAGE_V2 must be enabled.
+ifeq (${ARCH},aarch32)
+    ifeq (${LOAD_IMAGE_V2}, 0)
+        $(error "For AArch32, LOAD_IMAGE_V2 must be enabled.")
+    endif
+endif
+
+
 ################################################################################
 # Process platform overrideable behaviour
 ################################################################################