juno: Increase BL2 max size

Version 1.4.7 of libfdt is bigger than the current one (1.4.2) and the
current reserved space for BL2 in Juno isn't enough to fit the Trusted
Firmware when compiling with clang or armclang.

Change-Id: I7b73394ca60d17f417773f56dd5b3d54495a45a8
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

plat/arm/board/juno/include/platform_def.h

@@ -142,7 +142,7 @@
 # define PLAT_ARM_MAX_BL2_SIZE		0x1C000
 #endif
 #else
-# define PLAT_ARM_MAX_BL2_SIZE		0xE000
+# define PLAT_ARM_MAX_BL2_SIZE		0xF000
 #endif
 
 /*