soc: amlogic: canvas: add missing put_device() call in meson_canvas_get()

if of_find_device_by_node() succeed, meson_canvas_get() doesn't have
a corresponding put_device(). Thus add put_device() to fix the exception
handling for this function implementation.

Fixes: 382f8be0 ("soc: amlogic: canvas: Fix meson_canvas_get when probe failed")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20201117011322.522477-1-yukuai3@huawei.com