ARM: dts: msm: Add support for CPU clock for sdxpoorwills

Add support for APCS clock controller by replacing dummy
cpu clock driver node with actual cpu clock driver node.

Change-Id: I11f97644d1eb9454f89bddaf49c602ede541c7f9
Signed-off-by: Amit Nischal <anischal@codeaurora.org>