Drop mISDN userspace tools

This is unsupported for quite a while and nobody should be using this.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

src/setup/setup.h

@@ -32,7 +32,6 @@ int handleadminpassword(void);
 
 /* misc.c */
 int writehostsfiles(void);
-int handleisdn(void);
 
 /* keymap.c */
 int handlekeymap(void);