Use menuconfig objects: ISDN: CONFIG_ISDN_CAPI

Transform "depends on" into a simpler if-endif block style dependency.

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Cc: Karsten Keil <kkeil@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/isdn/Kconfig b/drivers/isdn/Kconfig
index a3c9a0343..cf906c8 100644
--- a/drivers/isdn/Kconfig
+++ b/drivers/isdn/Kconfig
@@ -57,8 +57,12 @@
 	  hardware, see <http://www.capi.org/>.  This is needed for AVM's set
 	  of active ISDN controllers like B1, T1, M1.
 
+if ISDN_CAPI
+
 source "drivers/isdn/capi/Kconfig"
 
 source "drivers/isdn/hardware/Kconfig"
 
+endif # ISDN_CAPI
+
 endif # ISDN