f2fs: make sure trace all f2fs_issue_flush

The root device's issue flush trace is missing,
add it and tracing the result from submit.

Fixes d50aaeec90 ("f2fs: show actual device info in tracepoints")
Signed-off-by: Kinglong Mee <[email protected]>
Reviewed-by: Chao Yu <[email protected]>
Signed-off-by: Jaegeuk Kim <[email protected]>
2 files changed