process_suspend_info - which handles the RESYNCING request - must not
reply until all writes which were initiated before the request arrived,
have completed.

As a by-product, all process_* functions now take mddev as their
first arguement making it uniform.
Signed-off-by: NGoldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NNeilBrown <neilb@suse.com>