Revert "md: do not progress the resync process if the stripe was blocked"

This reverts commit df10cfbc4d7ab93260d997df754219d390d62a9d.

This patch was based on a misunderstanding and risks introducing a busy-wait loop.
So revert it.

Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

diff --cc drivers/md/raid5.c
Simple merge