disp: msm: sde: force toggle gdsc during pd disable

During crtc_disable, gdsc toggle will not happen if
external vote is present. The current detection of external
vote might not result in gdsc toggle if there is a delay
in removing the genpd vote from rotator. This change
adds additional external vote check to handle such
scenarios.

Change-Id: I1bed408b13180703bfccffe40f5a1be2280645c7
Signed-off-by: Yashwanth <yvulapu@codeaurora.org>