Synchronise arch.h and arch_helpers.h with TF-A-Tests

The headers forked at some point in the past and have diverged a lot. In
order to make it easier to share code between TF-A-Tests and TF-A, this
patch synchronises most of the definitions in the mentioned headers.

This is not a complete sync, it has to be followed by more cleanup.

This patch also removes the read helpers for the AArch32 instructions
ats1cpr and ats1hr (they are write-only).

Change-Id: Id13ecd7aeb83bd2318cd47156d71a42f1c9f6ba2
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/plat/arm/common/arm_common.c b/plat/arm/common/arm_common.c
index b72dd20..56ad8ae 100644
--- a/plat/arm/common/arm_common.c
+++ b/plat/arm/common/arm_common.c
@@ -128,10 +128,10 @@
 	/*
 	 * Initialize CNTFRQ register in Non-secure CNTBase frame.
 	 * This is only required for Juno, because it doesn't follow ARM ARM
-	 * in that the value updated in CNTFRQ is not reflected in CNTBASE_CNTFRQ.
-	 * Hence update the value manually.
+	 * in that the value updated in CNTFRQ is not reflected in
+	 * CNTBASEN_CNTFRQ. Hence update the value manually.
 	 */
-	mmio_write_32(ARM_SYS_CNT_BASE_NS + CNTBASE_CNTFRQ, freq_val);
+	mmio_write_32(ARM_SYS_CNT_BASE_NS + CNTBASEN_CNTFRQ, freq_val);
 #endif
 }
 #endif /* ARM_SYS_TIMCTL_BASE */