staging/rtl81*: build as loadable modules only

These 3 drivers contain much duplicated (triplicated) code, so
building them as built-in results in many errors like:

(.text+0x1b160): multiple definition of `ieee80211_sta_ps_sleep'

Prevent this configuration by making them all buildable only as
loadable modules (similar to the vt665[56] patch last week).

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/staging/rtl8187se/Kconfig b/drivers/staging/rtl8187se/Kconfig
index 1b3103f..3162aab 100644
--- a/drivers/staging/rtl8187se/Kconfig
+++ b/drivers/staging/rtl8187se/Kconfig
@@ -1,6 +1,7 @@
 config R8187SE
 	tristate "RealTek RTL8187SE Wireless LAN NIC driver"
 	depends on PCI && WLAN
+	depends on m
 	select WIRELESS_EXT
 	select WEXT_PRIV
 	select EEPROM_93CX6