msm_fb: vsync events for legacy MDP 3.00 targets

Pieced together from current code in CAF. This is very specific to
MDP 3.00 targets that use the LCDC display controller, and it might
break horribly and badly on anything else.

Change-Id: I9d5fd9c47fd5524e8443237a4a4db4d9e9bf27cd
Signed-off-by: Rashed Abdel-Tawab <rashedabdeltawab@gmail.com>