clk: imx8mp: Fix clkout1/2 support

clk: imx8mp: Fix clkout1/2 support

The CLKOUTn may be fed from PLL1/2/3, but the PLL1/2/3 has to be enabled
first by setting PLL_CLKE bit 11 in CCM_ANALOG_SYS_PLLn_GEN_CTRL register.
The CCM_ANALOG_SYS_PLLn_GEN_CTRL bit 11 is modeled by plln_out clock. Fix
the clock tree and place the clkout1/2 under plln_sel instead of plain plln
to let the clock subsystem correctly control the bit 11 and enable the PLL
in case the CLKOUTn is supplied by PLL1/2/3.

Fixes: 43896f56b59e ("clk: imx8mp: add clkout1/2 support")
Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20241112013718.333771-1-marex@denx.de
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>