Enable ARMv8.6-ECV Self-Synch when booting to EL2

Enhanced Counter Virtualization, ECV, is an architecture extension introduced
in ARMv8.6. This extension allows the hypervisor, at EL2, to setup
self-synchronizing views of the timers for it's EL1 Guests. This patch pokes the
control register to enable this extension when booting a hypervisor at EL2.

Change-Id: I4e929ecdf400cea17eff1de5cf8704aa7e40973d
Signed-off-by: Jimmy Brisson <jimmy.brisson@arm.com>
diff --git a/include/arch/aarch64/arch_features.h b/include/arch/aarch64/arch_features.h
index 9bcf305..6b5d326 100644
--- a/include/arch/aarch64/arch_features.h
+++ b/include/arch/aarch64/arch_features.h
@@ -70,6 +70,12 @@
 		ID_AA64MMFR0_EL1_FGT_MASK) == ID_AA64MMFR0_EL1_FGT_SUPPORTED;
 }
 
+static inline unsigned long int get_armv8_6_ecv_support(void)
+{
+	return ((read_id_aa64mmfr0_el1() >> ID_AA64MMFR0_EL1_ECV_SHIFT) &
+		ID_AA64MMFR0_EL1_ECV_MASK);
+}
+
 /*
  * Return MPAM version:
  *