Convert CONFIG_FSL_ESDHC_PIN_MUX to Kconfig

This converts the following to Kconfig:
   CONFIG_FSL_ESDHC_PIN_MUX

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/mmc/fsl_esdhc_imx.c b/drivers/mmc/fsl_esdhc_imx.c
index 5ee3ce7..66caf68 100644
--- a/drivers/mmc/fsl_esdhc_imx.c
+++ b/drivers/mmc/fsl_esdhc_imx.c
@@ -1360,7 +1360,7 @@
 #if CONFIG_IS_ENABLED(OF_LIBFDT)
 __weak int esdhc_status_fixup(void *blob, const char *compat)
 {
-	if (IS_ENABLED(FSL_ESDHC_PIN_MUX) && !hwconfig("esdhc")) {
+	if (IS_ENABLED(CONFIG_FSL_ESDHC_PIN_MUX) && !hwconfig("esdhc")) {
 		do_fixup_by_compat(blob, compat, "status", "disabled",
 				sizeof("disabled"), 1);
 		return 1;