staging: greybus: hid: Constify lowlevel HID driver

staging: greybus: hid: Constify lowlevel HID driver

Since commit 52d225346904 ("HID: Make lowlevel driver structs const")
the lowlevel HID drivers are only exposed as const.

Take advantage of this to constify the underlying structure, too.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230130-hid-const-ll-driver-v1-9-3fc282b3b1d0@weissschuh.net
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>