nvme: add the Apple shared tag workaround to nvme_alloc_io_tag_set

Add the apple shared tag workaround to nvme_alloc_io_tag_set to prepare
for using that helper in the PCIe driver.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>