Staging: vt6655: iwctl.c: fix a sparse warning

fix a sparse warning and do some clean up.
iwctl.c:1846:35: expected restricted gfp_t [usertype] flags

Signed-off-by: Jimmy Li <coder.liss@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>