clk: qcom: Move cxo/pxo/xo into dt files

Put these clocks into the dt files instead of registering them
from C code. This provides a few benefits. It allows us to
specify the frequency of these clocks at the board level instead
of hard-coding them in the driver. It allows us to insert an RPM
clock in between the consumers of the crystals and the actual
clock. And finally, it helps us transition the GCC driver to use
RPM clocks when that configuration is enabled.

Cc: Georgi Djakov <georgi.djakov@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>