tty: audit: remove unused variable

While building with W=1 we were getting build warning:
drivers/tty/tty_audit.c:149:16: warning: variable 'sessionid' set but not used

The local variable sessionid was only assigned the value of
current->sessionid but was never reused. On further inspection it turned
out that there is no need of audit_get_loginuid() also.
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/tty_audit.c

@@ -144,14 +144,8 @@ void tty_audit_tiocsti(struct tty_struct *tty, char ch)
 	if (tty_audit_push())
 		return;
 
-	if (audit_enabled) {
-		kuid_t auid;
-		unsigned int sessionid;
-
-		auid = audit_get_loginuid(current);
-		sessionid = audit_get_sessionid(current);
+	if (audit_enabled)
 		tty_audit_log("ioctl=TIOCSTI", dev, &ch, 1);
-	}
 }
 
 /**