add user voltage control from motley-git Nexus 7 kernel source

Signed-off-by: drgravy <drg113001@gmail.com>
tf700t: Restore CM asusdec changes

http://review.cyanogenmod.org/#/c/31907
http://review.cyanogenmod.org/#/c/32132
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>

Change-Id: I9edf92abcd6a6f8bc35428fc210d8e6247e12983