This reverts commit c550e25bca660ed2554cbb48d32b82d0bb98e4b1.
Commit c550e25bca660ed2554cbb48d32b82d0bb98e4b1 ("f2fs: use flush
command instead of FUA for zoned device") used additional flush
command to keep write order.
Since Commit dd291d77cc90eb6a86e9860ba8e6e38eebd57d12 ("block:
Introduce zone write plugging") has enabled the block layer to
handle this order issue, there is no need to use flush command.
Signed-off-by: Wenjie Cheng <cwjhust@xxxxxxxxx>