rtlwifi: rtl8192cu: Add routine trx

Add routine rtlwifi/rtl8192cu/trx.c. This routine differs from the rtl8192ce
file of the same name.

Signed-off-by: George <george0505@realtek.com>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>