drivers: msm: Fix a handful of compiler warnings

Compiling the kernel with the -O2 GCC flag reveals a number
of warnings relating to potentially uninitialized variables
and other edge cases.

Change-Id: I3758dbe1af276d79f55188b9f2db850c730acb80
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>