clk: imx8mp: add clkout1/2 support

clkout1 and clkout2 allow to supply clocks from the SoC to the board,
which is used by some board designs to provide reference clocks.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Abel Vesa <abel.vesa@nxp.com>
Link: https://lore.kernel.org/r/20220427162131.3127303-1-l.stach@pengutronix.de


Signed-off-by: Abel Vesa <abel.vesa@nxp.com>