fabrics: Return errno mapped for fabrics error status

fabrics: Return errno mapped for fabrics error status

If discover has been failed due to a nvme status, it will be returned to
main() with mapped value for fabrics get log page command.

Now connect command related status cannot be added in this patch because
kernel is not currently returning the nvme status, it's instead
returning -EIO if fails.  errno for connect command can be added once
kernel is ready to return the proper value for nvme status.

Cc: Keith Busch <kbusch@kernel.org>
Cc: Chaitanya Kulkarni <chaitanya.Kulkarni@wdc.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com>
Reviewed-by: Chaitanya Kulkarni <chaianya.kulkarni@wdc.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>