[AX25]: Make ax2asc thread-proof

Ax2asc was still using a static buffer for all invocations which isn't
exactly SMP-safe.  Change ax2asc to take an additional result buffer as
the argument.  Change all callers to provide such a buffer.

Signed-off-by: Ralf Baechle DL5RB <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ax25/ax25_addr.c b/net/ax25/ax25_addr.c
index f4fa6df..dca179d 100644
--- a/net/ax25/ax25_addr.c
+++ b/net/ax25/ax25_addr.c
@@ -36,9 +36,8 @@
 /*
  *	ax25 -> ascii conversion
  */
-char *ax2asc(ax25_address *a)
+char *ax2asc(char *buf, ax25_address *a)
 {
-	static char buf[11];
 	char c, *s;
 	int n;