h5400 patch - merge h5400_bl.c to h5400.c

After some work, chatting on ML and IRC I propose a patch moving
backlight support on h5000 devices from h5400_bl.c to h5400.c.
The patch was tested on h5400 and h5500 devices to work fine. Nothing
new was introduced so there should be any problems with the patch.
The patch is complete - takes care of Kconfig and deletes h5400_bl.c

Many thanks to Mian Plizk and Paul Sokolovsky for help.

Comments are very welcome:)

Cheers
Michal Panczyk