Tegra: Introduce config for enabling NS access to L2/CPUECTRL regs

A new config, ENABLE_NS_L2_CPUECTRL_RW_ACCESS, allows Tegra platforms to
enable read/write access to the L2 and CPUECTRL registers. T210 is the
only platform that needs to enable this config for now.

Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
diff --git a/plat/nvidia/tegra/common/aarch64/tegra_helpers.S b/plat/nvidia/tegra/common/aarch64/tegra_helpers.S
index 264749b..2979b32 100644
--- a/plat/nvidia/tegra/common/aarch64/tegra_helpers.S
+++ b/plat/nvidia/tegra/common/aarch64/tegra_helpers.S
@@ -57,6 +57,7 @@
 	 */
 .macro	cpu_init_common
 
+#if ENABLE_NS_L2_CPUECTRL_RW_ACCESS
 	/* -------------------------------------------------------
 	 * Enable L2 and CPU ECTLR RW access from non-secure world
 	 * -------------------------------------------------------
@@ -65,6 +66,7 @@
 	msr	actlr_el3, x0
 	msr	actlr_el2, x0
 	isb
+#endif
 
 	/* --------------------------------
 	 * Enable the cycle count register