[mtd] Enable mtd test on host.

Change-Id: Ibd3c8638e8e24c80139f6e2bb861d4be49aad0b3
diff --git a/zircon/system/utest/BUILD.gn b/zircon/system/utest/BUILD.gn
index 1e6ac92..f5e0c65 100644
--- a/zircon/system/utest/BUILD.gn
+++ b/zircon/system/utest/BUILD.gn
@@ -202,10 +202,7 @@
       deps += [
         "$zx/system/dev/usb/usb-peripheral-test",
         "$zx/system/ulib/ftl-mtd/test",
-
-        # We can't run this test in CQ as it requires real/emulated MTD.
-        # Uncomment for local testing.
-        # "mtd",
+        "mtd",
       ]
     }
   }