sandbox: Enable mmc command and legacy images

The mmc command is useful for testing mmc disk images in sandbox, so
enable it. We also need to enable legacy images so that we can run tests
which use them.

Disable it for a few avb tests since MMC is not implemented there yet.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index de799b5..6c5bace 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -13,6 +13,7 @@
 CONFIG_FIT_RSASSA_PSS=y
 CONFIG_FIT_CIPHER=y
 CONFIG_FIT_VERBOSE=y
+CONFIG_LEGACY_IMAGE_FORMAT=y
 CONFIG_BOOTSTAGE=y
 CONFIG_BOOTSTAGE_REPORT=y
 CONFIG_BOOTSTAGE_FDT=y
@@ -72,6 +73,7 @@
 CONFIG_CMD_I2C=y
 CONFIG_CMD_LOADM=y
 CONFIG_CMD_LSBLK=y
+CONFIG_CMD_MMC=y
 CONFIG_CMD_MUX=y
 CONFIG_CMD_OSD=y
 CONFIG_CMD_PCI=y
diff --git a/configs/sandbox_flattree_defconfig b/configs/sandbox_flattree_defconfig
index 88aaddf..41453e0 100644
--- a/configs/sandbox_flattree_defconfig
+++ b/configs/sandbox_flattree_defconfig
@@ -11,6 +11,7 @@
 CONFIG_FIT=y
 CONFIG_FIT_SIGNATURE=y
 CONFIG_FIT_VERBOSE=y
+CONFIG_LEGACY_IMAGE_FORMAT=y
 CONFIG_BOOTSTAGE=y
 CONFIG_BOOTSTAGE_REPORT=y
 CONFIG_BOOTSTAGE_FDT=y
@@ -40,6 +41,7 @@
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_GPT=y
 CONFIG_CMD_I2C=y
+CONFIG_CMD_MMC=y
 CONFIG_CMD_OSD=y
 CONFIG_CMD_PCI=y
 CONFIG_CMD_REMOTEPROC=y