msm: mdss: change framebuffer split ratio at run time

This is to avoid kernel recompilation when a different
framebuffer split ratio is desired at run time. To
enable a new ratio, write the  desired value to
/sys/devices/virtual/graphics/fb0/msm_fb_split.
Changes will take effect only after client releases
all references to driver.

Change-Id: I4764399f80fc22ec5815a8e2818901189b3aaeb5
Signed-off-by: Jayant Shekhar <jshekhar@codeaurora.org>

Conflicts:
	drivers/video/msm/mdss/mdss_fb.c
msm: mdss: Change DSI backlight pwm_config to use nanoseconds

The DSI panel backlight is now configured using nanosecond duty cycle
and period for pwm. A nanosecond duty cycle is needed in order to satisfy
the granularity needed for 255 backlight levels and the DSI period. If the
pwm_period is very large, then a microsecond configuration is used.

Change-Id: I9551f52360f9d5da47ab7e2da6e039ad6f2695fb
Signed-off-by: Benet Clark <benetc@codeaurora.org>