scsi: qla2xxx: Modify NVMe include directives

Since struct sg_table is used in nvme-fc-driver.h, include
<linux/scatterlist.h> from that header file.

Since no definitions or declarations from <linux/blk-mq.h> are used in the
qla_nvme.h header file, do not include <linux/blk-mq.h> from that header
file.

Cc: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Himanshu Madhani <hmadhani@marvell.com>
Reviewed-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>