staging: rtl8188eu: remove is_{multicast,broadcast}_mac_addr

Remove custom is_multicast_mac_addr() and is_broadcast_mac_addr().
Use is_multicast_ether_addr() instead.

By definition the broadcast address is also a multicast address.
is_multicast_ether_addr() returns true for broadcast addresses.
Hence checking for multicast in the conditional is sufficient.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>