drm/msm/sde: store connector list associated with commit state

DRM framework pushes the commit with state and attaches
all the connectors and crtc associated with this state. SDE
crtc module resets the connectors associated with crtc during
this state processing (prepare_commit) phase. A retire fence
might triggered at the same time and it can try to access this
resent connector list. Such race condition will lead to fence
timeline update skip. Such cases can be avoided by storing
connector list into crtc object and retrieve it when fence
is ready to signal.

Change-Id: I87347a745413b422d26187000c1773ed7088002a
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>