msm: Display: Remove backlight/Panel-reset control from PMIC init function.

Add new API to control the backlight and reset GPIOs for the panel
that are part of PMIC. This is needed to support "continuous Splash
Screen feature".

Add new variable to enable "Continuous Splash Screen feature"
on 8960 chipset.

Change-Id: Id3da8643dc457e225ad7808257582e05b5e92800
Signed-off-by: Chandan Uddaraju <chandanu@codeaurora.org>