vexpress64: Add MMC card to the BOOT_TARGET_DEVICES of FVP

Add MMC disk to FVP's BOOT_TARGET_DEVICES. This allows the user to boot
from MMC devices.

Signed-off-by: Wei Chen <wei.chen@arm.com>
Signed-off-by: Qi Feng <qi.feng@arm.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/include/configs/vexpress_aemv8.h b/include/configs/vexpress_aemv8.h
index 43f7e45..24d8ca0 100644
--- a/include/configs/vexpress_aemv8.h
+++ b/include/configs/vexpress_aemv8.h
@@ -148,6 +148,12 @@
 #define FUNC_VIRTIO(func)
 #endif
 
+#ifdef CONFIG_CMD_MMC
+#define FUNC_MMC(func)	func(MMC, mmc, 0)
+#else
+#define FUNC_MMC(func)
+#endif
+
 /*
  * Boot by loading an Android image, or kernel, initrd and FDT through
  * semihosting into DRAM.
@@ -204,6 +210,7 @@
 	func(SMH, smh, na)		\
 	func(MEM, mem, na)		\
 	FUNC_VIRTIO(func)		\
+	FUNC_MMC(func)			\
 	func(PXE, pxe, na)		\
 	func(DHCP, dhcp, na)