Staging: xgifb: Fixed coding style issues in vb_def.h

I've removed all the warnings given by checkpatch.pl in vb_def.h and
also changed the indentation of pretty much the entire file so that it
is more consistent.
Signed-off-by: Daniel Kenji Toyama <kenji.toyama@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>