e11232: USDHC: uSDHC setting requirement for IPG_CLK and AHB_BUS clocks

Description: uSDHC AHB_BUS and IPG_CLK clocks must be synchronized.
Due to current physical design implementation, AHB_BUS and IPG_CLK must come from
same clock source to maintain clock sync.
Workaround: Set AHB_BUS and IPG_CLK to clock source from PLL1.

After sys1_pll_266m gate off/on, seems need to sync the USDHC AHB bus and USDHC IPG_clk again. (Here usdhc AHB BUS source from nand_usdhc_bus.)
This sync is handle by hardware, and maybe need some time, during this sync period, usdhc operation may has issue.

I just double check our local v5.10 branch, already revert the commit b04383b6 (clk: imx8mq: Define gates for pll1/2 fixed dividers).
So to fix this issue, one method is revert this patch, another method is keep the 'nand_usdhc_bus' always on. Add change like this:

Signed-off-by: Angus Ainslie <angus@akkea.ca>
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