The histogram support mixes _irqsave and _irq, causing the following
smatch warning:

     drivers/media/platform/renesas/vsp1/vsp1_histo.c:153 histo_stop_streaming()
     warn: mixing irqsave and irq

The histo_stop_streaming() calls spin_lock_irqsave() followed by
wait_event_lock_irq(). The former hints that interrupts may be disabled
by the caller, while the latter reenables interrupts unconditionally.
This doesn't cause any real bug, as the function is always called with
interrupts enabled, but the pattern is still incorrect.

Fix the problem by using spin_lock_irq() instead of spin_lock_irqsave()
in histo_stop_streaming(). While at it, switch to spin_lock_irq() and
spin_lock() as appropriate elsewhere.

Fixes: 99362e32 ("[media] v4l: vsp1: Add histogram support")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-renesas-soc/164d74ff-312c-468f-be64-afa7182cd2f4@moroto.mountain/Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>