input: synaptics_dsx: Propagating security fixes from msm-4.9

This commit is a squash of below security fixes from the
branch msm-4.9.

c263f2b input: touchscreen: synaptics_dsx: Remove fw_update sysfs
entries.
bf1fb21 input: synaptics_dsx: protect tmpbuf allocation.
4629a83 input: synaptics_dsx: reallocate buffer under lock.
c14afef input: touchpanel: fix current leakage when suspend.

Change-Id: I62e757ef3a92203a80fc390aca2107ade625d796
Signed-off-by: Vevek Venkatesan <vevekv@codeaurora.org>