scsi: qedf: Change the debug parameter permission to read & write

Change the debug parameter permission to read & write.  Gives flexibility
to change the debug verbosity dynamically.

Link: https://lore.kernel.org/r/20200907121443.5150-2-jhasan@marvell.com


Signed-off-by: Javed Hasan <jhasan@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>