net: ethernet: use sysfs_emit() to instead of scnprintf()

Follow the advice of the Documentation/filesystems/sysfs.rst and show()
should only use sysfs_emit() or sysfs_emit_at() when formatting the
value to be returned to user space.

Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/202212051918564721658@zte.com.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/ethernet/eth.c

@@ -398,7 +398,7 @@ EXPORT_SYMBOL(alloc_etherdev_mqs);
 
 ssize_t sysfs_format_mac(char *buf, const unsigned char *addr, int len)
 {
-	return scnprintf(buf, PAGE_SIZE, "%*phC\n", len, addr);
+	return sysfs_emit(buf, "%*phC\n", len, addr);
 }
 EXPORT_SYMBOL(sysfs_format_mac);