Revert "storage: For FS pool check for properly formatted target volume"

The check does not work properly (crashes) with netfs filesystems and
also checking that a device is not empty when attempting to mount a
filesystem is not very usefull since the mount will fail anyways.

As the code would improve only a very minor corner case I don't really
see a reason to have this code at all.

This code would also fail if libvirt is compiled without support for
blkid and without parted.

This reverts commit a11fd697.

src/storage/storage_backend_fs.c

@@ -605,17 +605,8 @@ static int
 virStorageBackendFileSystemStart(virConnectPtr conn ATTRIBUTE_UNUSED,
                                  virStoragePoolObjPtr pool)
 {
-    const char *format =
-        virStoragePoolFormatFileSystemTypeToString(pool->def->source.format);
-    const char *path = pool->def->source.devices[0].path;
-
-    if (pool->def->type == VIR_STORAGE_POOL_DIR)
-        return 0;
-
-    if (!virStorageBackendDeviceIsEmpty(path, format, false))
-        return -1;
-
-    if (virStorageBackendFileSystemMount(pool) < 0)
+    if (pool->def->type != VIR_STORAGE_POOL_DIR &&
+        virStorageBackendFileSystemMount(pool) < 0)
         return -1;
 
     return 0;