rtlwifi: Fix randconfig build error with next-20140930

Configuration randconfig-1412075201 gets an error because driver rtl8821ae
depends on driver btcoexist, but Kconfig does not select it.
Reported-by: Jim Davis <jim.epost@gmail.com>
Cc: Jim Davis <jim.epost@gmail.com>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rtlwifi/Kconfig

@@ -97,6 +97,7 @@ config RTL8821AE
 	depends on PCI
 	select RTLWIFI
 	select RTLWIFI_PCI
+	select RTLBTCOEXIST
 	---help---
 	This is the driver for Realtek RTL8i821AE/RTL8812AE 802.11av PCIe
 	wireless network adapters.
@@ -146,7 +147,7 @@ config RTL8723_COMMON
 
 config RTLBTCOEXIST
 	tristate
-	depends on RTL8723AE || RTL8723BE
+	depends on RTL8723AE || RTL8723BE || RTL8821AE
 	default y
 
 endif