drm/msm/sde: move sde hw init to hw_init callback

Callbacks from the upper layer expect hardware initialization
logic to reside within the hw_init callback. Consolidate all hw
initialization to the hw_init callback and update the deinit and
destroy callbacks to match it.

Change-Id: I2ab32edae0e8586ddb4701b3d8c5cfde9e611cad
Signed-off-by: Clarence Ip <cip@codeaurora.org>