clk: msm: clock-gcc-californium: Replace cxo_clk_src with xo

cxo_clk_src and xo are both references to the same xo resource.
There should be only one reference to the single xo resource, so
remove cxo_clk_src from the driver and replace all its instances
with references to the xo clk.

Change-Id: Ib7ad1f60d5229e9f9e9866c33da6981fa8393e96
Signed-off-by: Devesh Jhunjhunwala <deveshj@codeaurora.org>