media: imx: imx8mq-mipi-csi2: remove wrong irq config write operation

The place where this register writel() that masks one interrupt is placed
does not guarantee that the device is powered so that's not allowed.
Moreover imx8mq_mipi_csi_start_stream() masks the interrupt anyway so the
write is not even needed. Remove it as this is a mistake that slipped in
with the driver.

Fixes: f33fd8d7 ("media: imx: add a driver for i.MX8MQ mipi csi rx phy and controller")
Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>