utils: fs: skip shrink/extend operation for fat

fat does not support this operation, skip it

src/utils/fs.py

@@ -104,6 +104,8 @@ def ogReduceFs(disk, part):
         ret = _reduce_resize2fs(partdev)
     elif fstype == 'ntfs':
         ret = _reduce_ntfsresize(partdev)
+    elif fstype == 'vfat':
+        ret = 0
     else:
         ret = -1
         logging.error(f'Unable to shrink filesystem at {partdev}. '
@@ -127,6 +129,8 @@ def ogExtendFs(disk, part):
         _extend_resize2fs(partdev)
     elif fstype == 'ntfs':
         _extend_ntfsresize(partdev)
+    elif fstype == 'vfat':
+        pass
     else:
         logging.error(f'Unable to grow filesystem at {partdev}. '
 		      f'Unsupported filesystem "{fstype}".')