media: rzv2h-ivc: Fix AXIRX_VBLANK register write

media: rzv2h-ivc: Fix AXIRX_VBLANK register write

According to the documentation there are writable reserved bits in the
register and those should not be set to 0. So use `rzv2h_ivc_update_bits()`
with a proper bitmask.

Cc: stable@vger.kernel.org
Fixes: f0b3984d821b ("media: platform: Add Renesas Input Video Control block driver")
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Barnabás Pőcze <barnabas.pocze+renesas@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi+renesas@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>