Add macro to test for minimum architecture version

The macro concisely expresses and requires architecture version to be at
least as required by its arguments. This would be useful when extending
Trusted Firmware functionality for future architecture revisions.

Replace similar usage in the current code base with the new macro.

Change-Id: I9dcd0aa71a663eabd02ed9632b8ce87611fa5a57
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

include/lib/utils_def.h

@@ -73,4 +73,12 @@
 # define ULL(_x)	(_x##ull)
 #endif
 
+/*
+ * Test for the current architecture version to be at least the version
+ * expected.
+ */
+#define ARM_ARCH_AT_LEAST(_maj, _min) \
+	((ARM_ARCH_MAJOR > _maj) || \
+	 ((ARM_ARCH_MAJOR == _maj) && (ARM_ARCH_MINOR >= _min)))
+
 #endif /* __UTILS_DEF_H__ */

lib/locks/exclusive/aarch64/spinlock.S

@@ -9,7 +9,7 @@
 	.globl	spin_lock
 	.globl	spin_unlock
 
-#if (ARM_ARCH_MAJOR > 8) || ((ARM_ARCH_MAJOR == 8) && (ARM_ARCH_MINOR >= 1))
+#if ARM_ARCH_AT_LEAST(8, 1)
 
 /*
  * When compiled for ARMv8.1 or later, choose spin locks based on Compare and