Revert "drm: msm: Enable asynchronous driver probing"

This reverts commit 91601236.

DRM display driver can't afford to have async probe, As the execution can
be delayed and there are other critical operation which is required to be
completed during probe.

Change-Id: I8adf417e7a8d49f9a49916fe7b96033b93b7daf4
Signed-off-by: Rahul Sharma <rahsha@codeaurora.org>