ax25: move from strlcpy with unused retval to strscpy

Follow the advice of the below link and prefer 'strscpy' in this
subsystem. Conversion is 1:1 because the return value is not used.
Generated by a coccinelle script.

Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20220818210206.8299-1-wsa+renesas@sang-engineering.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/ax25/af_ax25.c

@@ -778,7 +778,7 @@ static int ax25_getsockopt(struct socket *sock, int level, int optname,
 		ax25_dev = ax25->ax25_dev;
 
 		if (ax25_dev != NULL && ax25_dev->dev != NULL) {
-			strlcpy(devname, ax25_dev->dev->name, sizeof(devname));
+			strscpy(devname, ax25_dev->dev->name, sizeof(devname));
 			length = strlen(devname) + 1;
 		} else {
 			*devname = '\0';