nvme: fix max_segments integer truncation

nvme: fix max_segments integer truncation

The block layer uses an unsigned short for max_segments.  The way we
calculate the value for NVMe tends to generate very large 32-bit values,
which after integer truncation may lead to a zero value instead of
the desired outcome.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Jeff Lien <Jeff.Lien@hgst.com>
Tested-by: Jeff Lien <Jeff.Lien@hgst.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Orabug: 24928835
Cherry picked commit: 45686b6198bd824f083ff5293f191d78db9d708a
Conflicts:
	UEK4 QU2 nvme module doesn't have core.c file. All the functions
resides in pci.c. Hence, this patch is manually ported to the respective
function in pci.c
	drivers/nvme/host/core.c

Signed-off-by: Ashok Vairavan <ashok.vairavan@oracle.com>