drm/msm: remove 5us wait from mode-2 sequence

Remove 5us wait (a software workaround) from mode-2
from sde rsc. This wait is not needed on all
updated hardware revs.

Change-Id: If5c3a47eda31fc164e59dbff747b92b934cdcfbc
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>