scsi: qla2xxx: Correctly report max/min supported speeds

This patch fixes reported speed for min_link and max_supported speed. Also
rename sysfs nodes link_speed and max_supported to be consistent with
{min|max}_suuported_speed.

Signed-off-by: Joe Carnuccio <joe.carnuccio@cavium.com>
Signed-off-by: Mike Hernandez <mhernandez@marvell.com>
Signed-off-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>