fix(cpus): modify the fix for Cortex-A75 erratum 764081

Apply the mitigation only for the revision and variant
mentioned in the SDEN.

SDEN Documentation:
https://developer.arm.com/documentation/SDEN859515/latest

Change-Id: Ifda1f4cb32bdec9a9af29397ddc03bf22a7a87fc
Signed-off-by: Sona Mathew <sonarebecca.mathew@arm.com>
diff --git a/lib/el3_runtime/aarch64/context_mgmt.c b/lib/el3_runtime/aarch64/context_mgmt.c
index 218ad11..6210356 100644
--- a/lib/el3_runtime/aarch64/context_mgmt.c
+++ b/lib/el3_runtime/aarch64/context_mgmt.c
@@ -89,13 +89,13 @@
 					| SCTLR_NTWI_BIT | SCTLR_NTWE_BIT;
 	}
 
-#if ERRATA_A75_764081
 	/*
 	 * If workaround of errata 764081 for Cortex-A75 is used then set
 	 * SCTLR_EL1.IESB to enable Implicit Error Synchronization Barrier.
 	 */
-	sctlr_elx |= SCTLR_IESB_BIT;
-#endif
+	if (errata_a75_764081_applies()) {
+		sctlr_elx |= SCTLR_IESB_BIT;
+	}
 
 	/* Store the initialised SCTLR_EL1 value in the cpu_context */
 	write_ctx_sctlr_el1_reg_errata(ctx, sctlr_elx);
@@ -1070,14 +1070,16 @@
 			if ((scr_el3 & SCR_HCE_BIT) != 0U) {
 				/* Initialize SCTLR_EL2 register with reset value. */
 				sctlr_el2 = SCTLR_EL2_RES1;
-#if ERRATA_A75_764081
+
 				/*
 				 * If workaround of errata 764081 for Cortex-A75
 				 * is used then set SCTLR_EL2.IESB to enable
 				 * Implicit Error Synchronization Barrier.
 				 */
-				sctlr_el2 |= SCTLR_IESB_BIT;
-#endif
+				if (errata_a75_764081_applies()) {
+					sctlr_el2 |= SCTLR_IESB_BIT;
+				}
+
 				write_sctlr_el2(sctlr_el2);
 			} else {
 				/*