f2fs: fix to propagate error from f2fs_enable_checkpoint()

f2fs: fix to propagate error from f2fs_enable_checkpoint()

[ Upstream commit be112e7449a6e1b54aa9feac618825d154b3a5c7 ]

In order to let userspace detect such error rather than suffering
silent failure.

Fixes: 4354994f097d ("f2fs: checkpoint disabling")
Cc: stable@kernel.org
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
[ adapted error handling to use restore_gc ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>