Restore SDCARD_FS=m

This was removed incorrectly; some CTS tests on AOSP master (only) still
require the filesystem.

Change-Id: Ieea38e16a6dd957fd95d54c4f1599ea011369247
diff --git a/goldfish_defconfig.fragment b/goldfish_defconfig.fragment
index 1d2c0b3..2a7f522 100644
--- a/goldfish_defconfig.fragment
+++ b/goldfish_defconfig.fragment
@@ -6,6 +6,7 @@
 CONFIG_HW_RANDOM_VIRTIO=m
 CONFIG_MAC80211_HWSIM=m
 CONFIG_RTC_DRV_TEST=m
+CONFIG_SDCARD_FS=m
 CONFIG_SND_HDA_CODEC_REALTEK=m
 CONFIG_SND_HDA_INTEL=m
 CONFIG_TEST_STACKINIT=m