ARM: dts: msm: Update the opp device property for MSM8909

With a7ssmux-opp-store-vcorner would associate the CPU clock frequencies
with only the CPU0 core. Update the device node to use 'qcom,enable-opp' so
as to link cpu frequencies with all CPU cores.

Change-Id: I61e7746f09c2728d012c021cefd44fe85d7e1787
Signed-off-by: Taniya Das <tdas@codeaurora.org>