msm: mdss: perform DSI PHY s/w reset for 12nm PHY during unblank

Perform DSI PHY s/w reset during DSI ON sequence for 12nm DSI PHY.
This avoid DSI PLL unlock issues caused due to DSI PHY not powering
OFF completely when the MDSS GDSC doesn't toggle during previous
display OFF sequence.

Change-Id: I7015f183d1bdc8c315aef58827492c990f7e8161
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>