storage: disk: Default to 'ext2' for new volumes.

Currently, if no format is specified for a new disk volume, we pass the
invalid value "none" as the FS type to 'parted mkpart'.

There doesn't seem to be a way to have parted not format the drive, so
just default to using 'ext2' in this case: this shouldn't cause any harm,
since we are creating a new partition in the first place.

src/storage_conf.c

@@ -95,7 +95,7 @@ VIR_ENUM_IMPL(virStorageVolFormatFileSystem,
 
 VIR_ENUM_IMPL(virStoragePartedFsType,
               VIR_STORAGE_PARTED_FS_TYPE_LAST,
-              "none", "ext2", "fat16",
+              "ext2", "ext2", "fat16",
               "fat32", "linux-swap",
               "ext2", "ext2",
               "extended")