prism54: set netdev type to "wlan"

commit 8e3ffa471091c560deb6738ed9ab7445b7a5fd04 upstream.

Userspace uses the netdev devtype for stuff like device naming and type
detection.  Be nice and set it.  Remove the pointless #if/#endif around
SET_NETDEV_DEV too.

Signed-off-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>