sd: also set max_user_sectors when setting max_sectors

sd: also set max_user_sectors when setting max_sectors

sd can set a max_sectors value that is lower than the max_hw_sectors
limit based on the block limits VPD page.   While this is rather unusual,
it used to work until the max_user_sectors field was split out to cleanly
deal with conflicting hardware and user limits when the hardware limit
changes.  Also set max_user_sectors to ensure the limit can properly be
stacked.

Fixes: 4f563a64732d ("block: add a max_user_discard_sectors queue limit")
Reported-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mike Snitzer <snitzer@kernel.org>