rtlwifi: btcoexist: Add vendor definition for new btcoexist

Routine halbtc_get() will need to be able to get the vendor ID.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>