HID: asus: fix missing hid_is_usb() check

HID: asus: fix missing hid_is_usb() check

to_usb_interface() can only be used on a hid_device whose parent is really
USB; uhid can create devices that identify as being on BUS_USB, but don't
actually have a USB parent.
Fix the use of to_usb_interface() without a hid_is_usb() check.

I have verified that it is currently possible to trigger a kernel splat due
to this bug in an ASAN build, and that this commit fixes the issue.

Fixes: 00e005c952f7 ("hid-asus: check ROG Ally MCU version and warn")
Cc: stable@vger.kernel.org
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>