ARM: dts: imx51-babbage: Enable secure-reg-access

Add 'secure-reg-access' property to enable PMU and hardware counters
so that they can be properly used with the 'perf' tool.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx51-babbage.dts

@@ -396,6 +396,10 @@
 	status = "okay";
 };
 
+&pmu {
+	secure-reg-access;
+};
+
 &ssi2 {
 	status = "okay";
 };