ASoC: msm: Add check for NULL pointer and buffer overflow

Changes to add check for NULL pointer before they
get dereferenced and check for buffer overflows
to ensure out of bound indexes of arrays are not
accessed.

CRs-fixed: 628847 628850
Change-Id: I3fcebe07a7f9e7ff480857480fa0df2ada017c69
Signed-off-by: Aravind Kumar <akumark@codeaurora.org>