input: synaptics: add NULL pointer check

add null pointer exception check for pointers which
may be NULL after request for memory allocation and
may be deferenced.

This patch is propagated from msm-3.10 kernel
(commit: 5a734f6783bdb12fe696efe1c4668f50ea294054
input: synaptics: add NULL pointer check)
Also cleaned checkpatch warnings on msm-3.18 kernel.

CRs-Fixed: 712847
Change-Id: I59ee5b00b124bc49fcc5d9d8bbfcb393fa70de05
Signed-off-by: Sarada Prasanna Garnayak <c_sgarna@codeaurora.org>
Signed-off-by: Sudhakar Manapati <smanap@codeaurora.org>