msm: mdss: Add error handling in mdss_fb_no_update_notify_timer_cb

Return in case mfd is NULL to avoid NULL pointer dereference.

CRs-Fixed: 563125
Change-Id: I82415ed5f1f7b3d27796e9e3a0c96178aa54bdc5
Signed-off-by: Jayant Shekhar <jshekhar@codeaurora.org>
msm: mdss: add error check for iommu attach API

Iommu device attach api returns error code if it fails.
MDP driver will check this error code and fall back to
recovery path if device attach fails.

Change-Id: I2b9d2d3aa16bc814739e466e9fc5a2c51c7b2b4b
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>