sunxi-mmc: introduce new MMC_SUNXI_HAS_MODE_SWITCH option

Allwinner A64 has new mode but doesn't have a mode switch in CCM,
and CCM_MMC_CTRL_MODE_SEL_NEW is not defined, so compilation fails
if MMC_SUNXI_HAS_NEW_MODE is enabled

Introduce new MMC_SUNXI_HAS_MODE_SWITCH option to be able to ifdef usage
of CCM_MMC_CTRL_MODE_SEL_NEW

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
[jagan: update commit message]
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com> # Amarula A64-Relic
diff --git a/drivers/mmc/sunxi_mmc.c b/drivers/mmc/sunxi_mmc.c
index 147eb9b..b3526f5 100644
--- a/drivers/mmc/sunxi_mmc.c
+++ b/drivers/mmc/sunxi_mmc.c
@@ -176,7 +176,9 @@
 
 	if (new_mode) {
 #ifdef CONFIG_MMC_SUNXI_HAS_NEW_MODE
+#ifdef CONFIG_MMC_SUNXI_HAS_MODE_SWITCH
 		val = CCM_MMC_CTRL_MODE_SEL_NEW;
+#endif
 		setbits_le32(&priv->reg->ntsr, SUNXI_MMC_NTSR_MODE_SEL_NEW);
 #endif
 	} else if (!calibrate) {