Staging: xgifb: fix lots of sparse warnings

Fix many sparse warnings about data or functions being static.
Fix many sparse warnings about data or functions not being used
  (put them inside #if 0/#endif blocks).
Fix sparse warnings about 0 being used for NULL.
Fixed a small bit of source formatting when those lines were being
  modified anyway, but there is still lots of this yet to be done.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: devel@driverdev.osuosl.org
Cc: Arnaud Patard <apatard@mandriva.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>