NVMe: Increase the max transfer size when mdts is 0

This patch address the issue when IO with 128KB from FIO is split into
two parts, 124KB and 4KB, due to max transfer size(127KB). This degrades
the device performance.

Signed-off-by: Sathyavathi M <sathya.m@samsung.com>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>