media: rockchip/rga: Fix bad dma_free_attrs() parameter

In rga_remove(), dma_free_attrs is being passed the wrong
cpu address, which triggers an exception if the driver is
removed. Fix it.

Tested on a RK3399 platform, with a bind/unbind cycle.

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>