Move context management code to common location

The upcoming Firmware Update feature needs transitioning across
Secure/Normal worlds to complete the FWU process and hence requires
context management code to perform this task.

Currently context management code is part of BL31 stage only.
This patch moves the code from (include)/bl31 to (include)/common.
Some function declarations/definitions and macros have also moved
to different files to help code sharing.

Change-Id: I3858b08aecdb76d390765ab2b099f457873f7b0c
diff --git a/include/common/bl_common.h b/include/common/bl_common.h
index 0eec989..d8741c9 100644
--- a/include/common/bl_common.h
+++ b/include/common/bl_common.h
@@ -89,6 +89,26 @@
 	(_p)->h.attr = (uint32_t)(_attr) ; \
 	} while (0)
 
+/*******************************************************************************
+ * Constants to indicate type of exception to the common exception handler.
+ ******************************************************************************/
+#define SYNC_EXCEPTION_SP_EL0		0x0
+#define IRQ_SP_EL0			0x1
+#define FIQ_SP_EL0			0x2
+#define SERROR_SP_EL0			0x3
+#define SYNC_EXCEPTION_SP_ELX		0x4
+#define IRQ_SP_ELX			0x5
+#define FIQ_SP_ELX			0x6
+#define SERROR_SP_ELX			0x7
+#define SYNC_EXCEPTION_AARCH64		0x8
+#define IRQ_AARCH64			0x9
+#define FIQ_AARCH64			0xa
+#define SERROR_AARCH64			0xb
+#define SYNC_EXCEPTION_AARCH32		0xc
+#define IRQ_AARCH32			0xd
+#define FIQ_AARCH32			0xe
+#define SERROR_AARCH32			0xf
+
 #ifndef __ASSEMBLY__
 #include <cdefs.h> /* For __dead2 */
 #include <cassert.h>