media: rockchip: rga: Fix possible ERR_PTR dereference in rga_buf_init()

media: rockchip: rga: Fix possible ERR_PTR dereference in rga_buf_init()

rga_get_frame() can return ERR_PTR(-EINVAL) when buffer type is
unsupported or invalid. rga_buf_init() does not check the return value
and unconditionally dereferences the pointer when accessing f->size.

Add proper ERR_PTR checking and return the error to prevent
dereferencing an invalid pointer.

Fixes: 6040702ade23 ("media: rockchip: rga: allocate DMA descriptors per buffer")
Cc: stable@vger.kernel.org
Signed-off-by: Alper Ak <alperyasinak1@gmail.com>
Reviewed-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>