TF-A: Fix wrong register read for MPAM extension

This patch fixes wrong ID_AA64DFR0_EL1 register read instead of
ID_AA64PFR0_EL1 to detect support for MPAM extension.
It also implements get_mpam_version() function which returns
MPAM version as:
0x00: None Armv8.0 or later;
0x01: v0.1 Armv8.4 or later;
0x10: v1.0 Armv8.2 or later;
0x11: v1.1 Armv8.4 or later;

Change-Id: I31d776b1a1b60cb16e5e62296d70adb129d7b760
Reported-by: Matteo Zini <matteozini96@gmail.com>
Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>
diff --git a/lib/extensions/mpam/mpam.c b/lib/extensions/mpam/mpam.c
index e794f01..65601dd 100644
--- a/lib/extensions/mpam/mpam.c
+++ b/lib/extensions/mpam/mpam.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -7,20 +7,16 @@
 #include <stdbool.h>
 
 #include <arch.h>
+#include <arch_features.h>
 #include <arch_helpers.h>
 #include <lib/extensions/mpam.h>
 
-bool mpam_supported(void)
-{
-	uint64_t features = read_id_aa64dfr0_el1() >> ID_AA64PFR0_MPAM_SHIFT;
-
-	return ((features & ID_AA64PFR0_MPAM_MASK) != 0U);
-}
-
 void mpam_enable(bool el2_unused)
 {
-	if (!mpam_supported())
+	/* Check if MPAM is implemented */
+	if (get_mpam_version() == 0U) {
 		return;
+	}
 
 	/*
 	 * Enable MPAM, and disable trapping to EL3 when lower ELs access their
@@ -34,10 +30,11 @@
 	 * If EL2 is implemented and used, enable trapping to EL2.
 	 */
 	if (el2_unused) {
-		write_mpam2_el2(0);
+		write_mpam2_el2(0ULL);
 
-		if ((read_mpamidr_el1() & MPAMIDR_HAS_HCR_BIT) != 0U)
-			write_mpamhcr_el2(0);
+		if ((read_mpamidr_el1() & MPAMIDR_HAS_HCR_BIT) != 0U) {
+			write_mpamhcr_el2(0ULL);
+		}
 	} else {
 		write_mpam2_el2(MPAM2_EL2_TRAPMPAM0EL1 |
 				MPAM2_EL2_TRAPMPAM1EL1);