qemu: Add support for stack canary protection

Allow qemu users to enable stack protection. Since the virt platform
does not provide an RNG, use a basic, timer-based, canary generation,
similarly to FVP.

Increase SRAM size and BL2 size to fit images when stack protection is
enabled.

Notice that stack protection is not enabled by default in qemu.

Fixes ARM-software/tf-issues#568

Signed-off-by: Michalis Pappas <mpappas@fastmail.fm>
diff --git a/plat/qemu/include/platform_def.h b/plat/qemu/include/platform_def.h
index f8764fb..2f2ca6f 100644
--- a/plat/qemu/include/platform_def.h
+++ b/plat/qemu/include/platform_def.h
@@ -75,7 +75,7 @@
 #define NS_DRAM0_SIZE			0x3de00000
 
 #define SEC_SRAM_BASE			0x0e000000
-#define SEC_SRAM_SIZE			0x00040000
+#define SEC_SRAM_SIZE			0x00060000
 
 #define SEC_DRAM_BASE			0x0e100000
 #define SEC_DRAM_SIZE			0x00f00000
@@ -123,7 +123,7 @@
  * Put BL2 just below BL3-1. BL2_BASE is calculated using the current BL2 debug
  * size plus a little space for growth.
  */
-#define BL2_BASE			(BL31_BASE - 0x1D000)
+#define BL2_BASE			(BL31_BASE - 0x25000)
 #define BL2_LIMIT			BL31_BASE
 
 /*