tests/extmod: Update littlefs test output to match new library version.

The amount of free space on the VfsLfs2 filesystem after creating a large
file is reduced by 2 blocks in this test.

tests/extmod/vfs_lfs.py.exp

@@ -38,7 +38,7 @@ write 0
 write 1
 write 2
 write 3
-(1024, 1024, 30, 9, 9, 0, 0, 0, 0, 255)
+(1024, 1024, 30, 7, 7, 0, 0, 0, 0, 255)
 [('testbig2', 32768, 0, 16384), ('testdir', 16384, 0, 0), ('test', 32768, 0, 8)]
 [('testdir', 16384, 0, 0), ('test', 32768, 0, 8)]
 /