media: rockchip: rkcif: comply with minimum number of buffers requirement

media: rockchip: rkcif: comply with minimum number of buffers requirement

Each stream requires CIF_REQ_BUFS_MIN=1 buffers to enable streaming.
However, it failed with only one buffer provided.

Comply with the minimum number of buffers requirement and accept
exactly one buffer.

Fixes: 501802e2ad51 ("media: rockchip: rkcif: add abstraction for dma blocks")
Cc: stable@kernel.org
Tested-by: Paul Elder <paul.elder@ideasonboard.com>
Tested-by: Chen-Yu Tsai <wens@kernel.org>
Signed-off-by: Michael Riesch <michael.riesch@collabora.com>
Reviewed-by: Isaac Scott <isaac.scott@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>