drbd: don't set max_write_zeroes_sectors in decide_on_discard_support

fixup_write_zeroes always overrides the max_write_zeroes_sectors value
a little further down the callchain, so don't bother to setup a limit
in decide_on_discard_support.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Philipp Reisner <philipp.reisner@linbit.com>
Reviewed-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Tested-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
Link: https://lore.kernel.org/r/20240306140332.623759-6-philipp.reisner@linbit.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>