f2fs: set CP_TRIMMED_FLAG correctly

Don't set CP_TRIMMED_FLAG for non-zoned block device or discard
unsupported device, it can avoid to trigger unneeded checkpoint for
that kind of device.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>