msm: fb: Fix security bugs in msmfb_notify_update & msm_fb_ioctl.

msmfb_notify_update: Correct signature of msmfb_notify_update from
the ioctl declaration.

msm_fb_ioctl: Add appropriate null check for mfd data structure
before accessing it's members. This prevents null pointer accesses
in the driver.

CRs-Fixed: 526286
Change-Id: I731018057214fb0fa58c7617934100d2425617f8
Signed-off-by: Neti, Ravi Kumar <ravineti@codeaurora.org>

Conflicts:

	drivers/video/msm/msm_fb.c

Signed-off-by: Abhinav Gurram <c_abhina@codeaurora.org>
Merge "msm: fb: Fix security bugs in msmfb_notify_update & msm_fb_ioctl."