backlight: Add Frontpath ProGear HX1050+ driver

Add control of LCD backlight for Frontpath ProGear HX1050+.
Patch is based on http://downloads.sf.net/progear/progear-lcd-0.2.tar.gz


driver by M Schacht.

Signed-off-by: Marcin Juszkiewicz <openembedded@hrw.one.pl>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>