[PATCH] md: Restore 'remaining' count when retrying an write operation

When retrying a write due to barrier failure, we don't reset 'remaining', so
it goes negative and never hits 0 again.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>