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=[e-mail]/
Signed-off-by: Wolfram Sang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

net/ax25/af_ax25.c

···
 		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';