media: imx: imx7_mipi_csis: Add i.MX8MM support

The CSI-2 receiver in the i.MX8MM is a newer version of the one found in
the i.MX7. Differences are minimal, support it in the imx7_mipi_csis
driver.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Rui Miguel Silva <rmfrfs@gmail.com>
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>