msm: clock: Check arguments to clk_set_parent

Verify that the struct clk pointer is valid before accessing
its members.

Change-Id: I945b5b34267064c805853509e434454f513c601b
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>
msm: clock: Fix invalid pointer dereferences on error condition

Check whether a clock pointer is an error value before deferencing it.

Change-Id: I3fde1e5ef39f5a2ef905e6efafece53f4453ee58
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>