arm64: dts: imx8mm: Make osc_32k available in SPL

arm64: dts: imx8mm: Make osc_32k available in SPL

Since commit b4734c9c333b ("clk: imx: Convert clock-osc-* back to osc_*")
SPL takes a long time to load U-Boot proper on an imx8mm-evk board.

The reason for the long delay is because the osc_32k clock is not available
in the SPL phase.

Fix this problem by passing the 'bootph-all' and 'bootph-pre-ram'
properties to make the osc_32k clock available in SPL.

This also aligns with imx8mn and imx8mp-u-boot.dtsi files.

Fixes: b4734c9c333b ("clk: imx: Convert clock-osc-* back to osc_*")
Suggested-by: Marek Vasut <marex@denx.de>
Signed-off-by: Fabio Estevam <festevam@denx.de>
Reviewed-by:  Adam Ford <aford173@gmail.com>