msm: mdss: Move splash thread functionality

framebuffer and overlay drivers are tightly coupled with
splash thread functionality. This adds lots of code
related to continuous splash screen handling in
both drivers. Moving them to separate file cleans up
both drivers and allows to handle continuous splash screen
cases efficiently.

CRs-fixed: 605934
Change-Id: Id89bb281dbbf22e726cf5fd97e93f891e5c73f60
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>

Conflicts:
	drivers/video/msm/mdss/mdss_fb.c
	drivers/video/msm/mdss/mdss_fb.h
	drivers/video/msm/mdss/mdss_mdp_overlay.c
msm: mdss: fix race condition between shutdown thread and fb ioctl

Currently all entires into fb driver are synchronized with shutdown
context except fb ioctl context. fb ioctl is an asynchronous entry to
fb driver which can be called simultaneously from two different user
processes. Synchronize these fb ioctls and shutdown context to prevent
race condition.

Change-Id: I81ce48159fce69caabc3336d70df2bd15c4ee44b
CRs-Fixed: 640199
Signed-off-by: Ujwal Patel <ujwalp@codeaurora.org>

Conflicts:
	drivers/video/msm/mdss/mdss_fb.c
fix some fuckery