tests/extmod/vfs_fat_ramdisk: Add test for VFS.statvfs().

tests/extmod/vfs_fat_ramdisk.py

@@ -45,6 +45,7 @@ assert b"FOO_FILETXT" not in bdev.data
 assert b"hello!" not in bdev.data
 
 vfs = uos.VfsFat(bdev, "/ramdisk")
+print("statvfs:", vfs.statvfs("/ramdisk"))
 
 print("getcwd:", vfs.getcwd())
 

tests/extmod/vfs_fat_ramdisk.py.exp

+statvfs: (512, 512, 14, 14, 14, 0, 0, 0, 0, 255)
 getcwd: /ramdisk
 hello!
 getcwd: /ramdisk/foo_dir