soc: imx: imx8m-blk-ctrl: fix display clock for LCDIF2 power domain

LCDIF2 has its own display clock, use this one.

Fixes: 07614fed ("soc: imx: imx8m-blk-ctrl: Add i.MX8MP media blk-ctrl")
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Tested-by: Martyn Welch <martyn.welch@collabora.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>