imx8m: update clock root and fix core_sel

Update clock root table to let it be easy to configure clock at
very early stage. Also the core_sel mux parent should be A53 CLK
root and ARM PLL.

Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
2 files changed