icnss: Enable PMM_TCXO_CLK before switch to cxo

Enable PMM_TCXO_CLK before swith to cxo. Also, add
debug logs of reading WCSS_SR_PMM_SR_MSB register
multiple times to check whether ref clock is shut off
or not when xo disable command failed.

CRs-Fixed: 1082643
Change-Id: I1aae776d5e6cc8f1cc2af9278c0e3d6ac37804a9
Signed-off-by: Yuanyuan Liu <yuanliu@codeaurora.org>