qcom: clock-generic: Allow mux source switching without using safe parent

There are muxes that allow for changing sources without
having to use the intermediate safe parent. Add support
for the same.

CRs-Fixed: 690648
Change-Id: If0ffafaadeb9c5fc5647741e1e25e70d6ed8d40f
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>