msm: mdss: avoid check for ctl path number for sending panel commands

For command mode, we check for control path number to send the panel
OFF/LP1/LP2 commands. This causes issues when a command mode panel
is not driven on control path #0. Modify the check to make sure panel
commands are sent properly for all use cases using the split display
validity APIs.

Change-Id: Icbcf775020d4f65dc8bad8b3a84534842d114f0b
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>