Add mISDN driver

mISDN is a new modular ISDN driver, in the long term it should replace
the old I4L driver architecture for passiv ISDN cards.

Signed-off-by: Karsten Keil <kkeil@suse.de>
diff --git a/drivers/isdn/Kconfig b/drivers/isdn/Kconfig
index 66f946a..3d113c6 100644
--- a/drivers/isdn/Kconfig
+++ b/drivers/isdn/Kconfig
@@ -3,7 +3,7 @@
 #
 
 menuconfig ISDN
-	tristate "ISDN support"
+	bool "ISDN support"
 	depends on NET
 	depends on !S390
 	---help---
@@ -21,6 +21,8 @@
 
 if ISDN
 
+source "drivers/isdn/mISDN/Kconfig"
+
 menuconfig ISDN_I4L
 	tristate "Old ISDN4Linux (deprecated)"
 	---help---