The mux in the clkout path needs the current selected parent to
be enabled for the switch to work. Use the correct mux type
to have the clk framework take care of this requirement.

Fixes: c1ae5c6f ("clk: imx8mm: add clkout1/2 support")
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Abel Vesa <abel.vesa@nxp.com>
Link: https://lore.kernel.org/r/20210628211554.2510238-1-l.stach@pengutronix.deSigned-off-by: Abel Vesa <abel.vesa@nxp.com>