char: virtio: constify attribute_group structures.

attribute_group are not supposed to change at runtime. All functions
working with attribute_group provided by <linux/sysfs.h> work with
const attribute_group. So mark the non-const structs as const.

Signed-off-by: Arvind Yadav <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/char/virtio_console.c

···
 	NULL
 };
 
-static struct attribute_group port_attribute_group = {
+static const struct attribute_group port_attribute_group = {
 	.name = NULL,		/* put in device directory */
 	.attrs = port_sysfs_entries,
 };