media: rockchip/rga: do proper error checking in probe

The latest fix for probe error handling contained a typo that causes
probing to fail with the following message:

  rockchip-rga: probe of ff680000.rga failed with error -12

This patch fixes the typo.

Fixes: e58430e1

 (media: rockchip/rga: fix error handling in probe)
Reviewed-by: Dragan Simic <dragan.simic@gmail.com>
Signed-off-by: Kyle Copperfield <kmcopper@danwin1210.me>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>