drisw: Fix invalid pointer arithmetic

Use of void * in pointer arithmetic is illegal, use char * instead.
Fixes: cf54bd5e8381dba18d52fe438acda20cc1685bf3 ("drisw: use shared memory when possible")

Reviewed-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>
1 file changed