gma500: cdv_intel_lvds: #if 0 currently unused functions

cdv_intel_lvds_set_brightness() is only used in commented out code in
cdv_set_brightness().

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>