msm_fb: display: add panel's late_init

 Some panels need to be initialized after panel is on.
 Add late_init to support this feature.

 CRs-fixed: 433011
 Change-Id: I73c623d1fe52363f070af79ce4bf7774cd84689e
 Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>