[SCSI] bfa: Support for FC BB credit recovery

This patch includes changes to  1) Enable/disable fc credit recovery on
Brocade FC adapter port operating at max supported speed. 2) Get credit
recovery status and stats related to credit loss and recovered credits

Signed-off-by: Vijaya Mohan Guvva <vmohan@brocade.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>