msm: mdss: Find a stable sysfs node for the gamma interface

Move sysfs files to /sys/module/dsi_panel/*
dts: lm3630: lower min brightness to 1

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>
dts: lm3630: lower blmap for lower brightness levels

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>