msm: mdss: fix conditional check for panel LP configuration

Add change to correct the conditional check for entering the
panel in and out of LP configurations. Remove the unused enum
structure related to panel blank status.

Change-Id: Ic1140eafcc7cdd8d64c107bddc824eeca844462d
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>