media: mediatek: vcodec: Fix a resource leak related to the scp device in FW initialization

On Mediatek devices with a system companion processor (SCP) the mtk_scp
structure has to be removed explicitly to avoid a resource leak.
Free the structure in case the allocation of the firmware structure fails
during the firmware initialization.

Fixes: 53dbe085 ("media: mtk-vcodec: potential null pointer deference in SCP")
Cc: stable@vger.kernel.org
Signed-off-by: Jiasheng Jiang <jiashengjiangcool@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>