ARM: sunxi: Fix build break when CONFIG_MMC is not defined

BOOT_TARGET_DEVICES includes MMC unconditionally. This breaks when
CONFIG_CMD_MMC is not defined. Use a secondary macro to conditionally
include it when CONFIG_MMC is enabled, as we do for CONFIG_AHCI.

This is used when we want to use uart0 from port F, which conflicts
with mmc0.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Ian Campbell <ijc@hellion.org.uk>

include/configs/sunxi-common.h

@@ -226,6 +226,12 @@
 	"pxefile_addr_r=0x43200000\0" \
 	"ramdisk_addr_r=0x43300000\0"
 
+#ifdef CONFIG_MMC
+#define BOOT_TARGET_DEVICES_MMC(func) func(MMC, mmc, 0)
+#else
+#define BOOT_TARGET_DEVICES_MMC(func)
+#endif
+
 #ifdef CONFIG_AHCI
 #define BOOT_TARGET_DEVICES_SCSI(func) func(SCSI, scsi, 0)
 #else
@@ -239,7 +245,7 @@
 #endif
 
 #define BOOT_TARGET_DEVICES(func) \
-	func(MMC, mmc, 0) \
+	BOOT_TARGET_DEVICES_MMC(func) \
 	BOOT_TARGET_DEVICES_SCSI(func) \
 	BOOT_TARGET_DEVICES_USB(func) \
 	func(PXE, pxe, na) \