md/raid5: fix init_stripe() inconsistencies

raid5: fix init_stripe() inconsistencies

1) remove_hash() is not necessary. We will only be called right after
   get_free_stripe(). There we have already a call to remove_hash().

2) Tracing prints out the sector of the freed stripe and not the sector
   that we want to initialize.

Signed-off-by: NeilBrown <neilb@suse.de>