Add missing RES1 bit in SCTLR_EL1

As per Section D7.2.81 in the ARMv8-A Reference Manual (DDI0487A Issue A.h),
bits[29:28], bits[23:22], bit[20] and bit[11] in the SCTLR_EL1 are RES1. This
patch adds the missing bit[20] to the SCTLR_EL1_RES1 macro.

Change-Id: I827982fa2856d04def6b22d8200a79fe6922a28e

include/lib/aarch64/arch.h

@@ -134,7 +134,7 @@
 			(1 << 4))
 
 #define SCTLR_EL1_RES1  ((1 << 29) | (1 << 28) | (1 << 23) | (1 << 22) | \
-			(1 << 11))
+			(1 << 20) | (1 << 11))
 #define SCTLR_AARCH32_EL1_RES1 \
 			((1 << 23) | (1 << 22) | (1 << 11) | (1 << 4) | \
 			(1 << 3))