media: verisilicon: Fix AV1 decoder clock frequency

The desired clock frequency was correctly set to 400MHz in the device tree
but was lowered by the driver to 300MHz breaking 4K 60Hz content playback.
Fix the issue by removing the driver call to clk_set_rate(), which reduce
the amount of board specific code.

Fixes: 003afda9 ("media: verisilicon: Enable AV1 decoder on rk3588")
Cc: stable@vger.kernel.org
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>