hv: vmbus: Constify struct kobj_type and struct attribute_group

vmbus_chan_group  and vmbus_chan_type are not modified. They are only
used in the helpers which take a const type parameter.

Constifying these structures and moving them to a read-only section can
increase over all security.

```
[Before]
   text   data    bss    dec    hex    filename
  20568   4699     48  25315   62e3    drivers/hv/vmbus_drv.o

[After]
   text   data    bss    dec    hex    filename
  20696   4571     48  25315   62e3    drivers/hv/vmbus_drv.o
```

Signed-off-by: Hongbo Li <[email protected]>
Reviewed-by: Naman Jain <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <[email protected]>

Author: Hongbo Li

drivers/hv/vmbus_drv.c

@@ -1803,12 +1803,12 @@ static umode_t vmbus_chan_attr_is_visible(struct kobject *kobj,
 	return attr->mode;
 }
 
-static struct attribute_group vmbus_chan_group = {
+static const struct attribute_group vmbus_chan_group = {
 	.attrs = vmbus_chan_attrs,
 	.is_visible = vmbus_chan_attr_is_visible
 };
 
-static struct kobj_type vmbus_chan_ktype = {
+static const struct kobj_type vmbus_chan_ktype = {
 	.sysfs_ops = &vmbus_chan_sysfs_ops,
 	.release = vmbus_chan_release,
 };