gma500: Extract BIOSisy stuff from psb_drv

This is too big already so lets rip out more of the device specific crud. It
also means we pull the ugly stuff that needs work out of our main line of
cleanup.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>