mwl8787: fix coding style for this switch

Signed-off-by: Bob Copeland <me@bobcopeland.com>
mwl8787: add __CHECK_ENDIAN__ to default cc flags

Lets sparse tell me all the stuff I forgot.

Signed-off-by: Bob Copeland <me@bobcopeland.com>
mwl8787: fix endian bugs

Found by sparse.

Signed-off-by: Bob Copeland <me@bobcopeland.com>