ISDN: remove uses of isdn_tty_revision

Commit "ISDN: i4l, remove cvs crap" removed definition of
isdn_tty_revision, but there is still a user. So this causes linking
errors. This was hidden from my radar because the variable was not
declared in any header. Instead isdn_common.c declares it locally.

So remove this variable also from isdn_common.c, because there is
really no way to find out the version. Git commit or tag is...
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Karsten Keil <isdn@linux-pingi.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/isdn/i4l/isdn_common.c

@@ -46,7 +46,6 @@ static DEFINE_MUTEX(isdn_mutex);
 static char *isdn_revision = "$Revision: 1.1.2.3 $";
 
 extern char *isdn_net_revision;
-extern char *isdn_tty_revision;
 #ifdef CONFIG_ISDN_PPP
 extern char *isdn_ppp_revision;
 #else
@@ -2351,8 +2350,6 @@ static int __init isdn_init(void)
 
 	strcpy(tmprev, isdn_revision);
 	printk(KERN_NOTICE "ISDN subsystem Rev: %s/", isdn_getrev(tmprev));
-	strcpy(tmprev, isdn_tty_revision);
-	printk("%s/", isdn_getrev(tmprev));
 	strcpy(tmprev, isdn_net_revision);
 	printk("%s/", isdn_getrev(tmprev));
 	strcpy(tmprev, isdn_ppp_revision);