arch/imx9: Increase uSDHC root clock to 400MHz

This is the nominal speed according to the TRM, and using higher
root clock gives more frequency selections (possible dividers) for
the SD card clock configuration.

Signed-off-by: Jukka Laitinen <jukka.laitinen@tii.ae>

Author: jlaitine

arch/arm64/src/imx9/imx9_usdhc.c

@@ -3453,7 +3453,7 @@ struct sdio_dev_s *imx9_usdhc_initialize(int slotno)
 
       /* Enable clocks */
 
-      imx9_ccm_configure_root_clock(CCM_CR_USDHC1, SYS_PLL1PFD1, 4);
+      imx9_ccm_configure_root_clock(CCM_CR_USDHC1, SYS_PLL1PFD1, 2);
       imx9_get_rootclock(CCM_CR_USDHC1, &priv->root_clock_freq);
       imx9_ccm_gate_on(CCM_LPCG_USDHC1, true);
 
@@ -3488,7 +3488,7 @@ struct sdio_dev_s *imx9_usdhc_initialize(int slotno)
 
       /* Enable clocks */
 
-      imx9_ccm_configure_root_clock(CCM_CR_USDHC2, SYS_PLL1PFD1, 4);
+      imx9_ccm_configure_root_clock(CCM_CR_USDHC2, SYS_PLL1PFD1, 2);
       imx9_get_rootclock(CCM_CR_USDHC2, &priv->root_clock_freq);
       imx9_ccm_gate_on(CCM_LPCG_USDHC2, true);