nvdimm: simplify revalidate_disk handling

The nvdimm block driver abuse revalidate_disk in a strange way, and
totally unrelated to what other drivers do.  Simplify this by just
calling nvdimm_revalidate_disk (which seems rather misnamed) from the
probe routines, as the additional bdev size revalidation is pointless
at this point, and remove the revalidate_disk methods given that
it can only be triggered from add_disk, which is right before the
manual calls.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>