Staging: rt2870: add device ID of MelCo.,Inc. WLI-UC-G301N

My wireless LAN module 'MelCo.,Inc. WLI-UC-G301N' works fine,
if the following line is added into 2870_main_dev.c.

Signed-off-by: Nobhiro KUSUNO <n-kusuno@fc4.so-net.ne.jp>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>