Revert "disp: msm: sde: add event to event_list after register is successful"

This reverts commit 91fc51777c67ddc92d0ba1fcddf6cd149f7a0560.
The original fix missed to add the client to list in cases when count is
larger than zero and client doesn't need to be deleted from list if
msm_register_event fails as it was not added to list yet.
Revert this change to upload the correct fix.

Change-Id: I00923d65387753b05b6b03efec109c019826f5d5
Signed-off-by: Ping Li <pingli@codeaurora.org>