msm_fb: mdss: Fix suspend/resume for panel driver

Avoid disabling video mode while sending OFF commands.
Add delay between the display reset line toggle
mechanism and GPIO display enable API for proper
reset of the panel.
Modify the PHY regulator control configuration sequence
for proper reset of the physical layer.

Change-Id: I2c890d52d773faab6020267121ea4557a59bd108
Signed-off-by: Chandan Uddaraju <chandanu@codeaurora.org>