Convert CONFIG_FSL_USDHC to Kconfig

This converts the following to Kconfig:
   CONFIG_FSL_USDHC

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/phycore-imx8mp_defconfig b/configs/phycore-imx8mp_defconfig
index fdc136c..758c288 100644
--- a/configs/phycore-imx8mp_defconfig
+++ b/configs/phycore-imx8mp_defconfig
@@ -81,7 +81,7 @@
 CONFIG_MMC_UHS_SUPPORT=y
 CONFIG_MMC_HS400_ES_SUPPORT=y
 CONFIG_MMC_HS400_SUPPORT=y
-CONFIG_FSL_ESDHC_IMX=y
+CONFIG_FSL_USDHC=y
 CONFIG_PHYLIB=y
 CONFIG_PHY_TI_DP83867=y
 CONFIG_DM_ETH=y