[SCSI] bfa: Add support for user to configure bandwidth on QoS priorities

Made changes to provide an option for user to configure the
bandwidth percentage for High/Medium/Low QoS priorities.

Signed-off-by: Sudarsana Reddy Kalluru <skalluru@brocade.com>
Signed-off-by: Krishna Gudipati <kgudipat@brocade.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>