arm64: dts: imx93: assign usdhc[1..3] root clock to 400MHz

1. Config SDHC1 clock 400MHz to support eMMC HS400ES mode
2. The original usdhc2 and usdhc3 root clock is 200MHz. Then WIFI
on usdhc3 at SDR104 mode can work under 200MHz. But if imx93 work
under Low Drive mode, the usdhc3 pad signal is not good under 200MHz,
SDR104 mode can't work stable. Need to downgrade to 133MHz to let
WIFI work stable. To cover all the cases, for Norminal Drive mode,
keep usdhc root at 400MHz, then card(SD/wifi) can work at SDR104 mode
under 200MHz to get the best performance. For Low Drive mode,
bootloader need override usdhc root clock to 266MHz, and the
card(SD/wifi) work at SDR104 mode under 133MHz, can work stable.

Reviewed-by: Sherry Sun <sherry.sun@nxp.com>
Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>