backlight: use exponential backlight control instead of linear.

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
dts: lm3630: lower min brightness to 1

Change-Id: I1d2e3860aa04460bf0c95fa2a7abf85ec4a6edf3
Signed-off-by: Dennis Rassmann <showp1984@gmail.com>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>

Conflicts:
	arch/arm/boot/dts/msm8974-hammerhead/msm8974-hammerhead-misc.dtsi
dts: lm3630: lower blmap for lower brightness levels

Change-Id: Ia7a0e3c365bf3518c0a1c0ec3c5ca889abd5e18a
Signed-off-by: Dennis Rassmann <showp1984@gmail.com>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>