feat(tc0): update Matterhorn ELP DVFS clock index

This allows the the Matterhorn ELP Arm core to operate at its
designated OPP.

Signed-off-by: Usama Arif <usama.arif@arm.com>
Change-Id: I7ccef0cfd079d630c3cfe7874590bf42789a1dca

fdts/tc0.dts

@@ -146,7 +146,7 @@
 			compatible = "arm,armv8";
 			reg = <0x700>;
 			enable-method = "psci";
-			clocks = <&scmi_dvfs 1>;
+			clocks = <&scmi_dvfs 2>;
 			cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
 		};