BugLink: http://bugs.launchpad.net/bugs/1655969

commit 82a301cb upstream.

Fixes: 90f5f7ad("md: Wait for md_check_recovery before attempting device
removal.")
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>