slcanpty: declare command buffer static

ASCII command buffer char buf[200] must be declared as static,
because it holds incomplete commands between pty2can() calls.
Without static it is not guaranteed, that buf retains the same
data between calls.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

slcanpty.c

@@ -68,7 +68,7 @@ int pty2can(int pty, int socket, struct can_filter *fi,
 {
 	int nbytes;
 	char cmd;
-	char buf[200];
+	static char buf[200];
 	char replybuf[10]; /* for answers to received commands */
 	int ptr;
 	struct can_frame frame;