treewide: Migrate CONFIG_FSL_ESDHC to Kconfig

Migrate the CONFIG_FSL_ESDHC option to Kconfig.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/configs/mx51evk_defconfig b/configs/mx51evk_defconfig
index 4eccf51..b7ed3ce 100644
--- a/configs/mx51evk_defconfig
+++ b/configs/mx51evk_defconfig
@@ -20,6 +20,7 @@
 CONFIG_CMD_DATE=y
 CONFIG_CMD_FAT=y
 CONFIG_ENV_IS_IN_MMC=y
+CONFIG_FSL_ESDHC=y
 CONFIG_MXC_SPI=y
 CONFIG_USB=y
 CONFIG_USB_STORAGE=y