clk: qcom: Always add factor clock for xo clocks

Currently the RPM/RPM-SMD clock drivers do not register the xo clocks,
so we should always add factor clock. When we later add xo clocks support
into the drivers, we should update this function to skip registration.
By doing so we avoid any DT dependencies.

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