scsi: qla2xxx: Use flag PFLG_DISCONNECTED.

There is already flag defined PFLG_DISCONNECTED, which is set
for PCI or register disconnect error condition. There is no need to have
flag PCI_ERR, which has same purpose. Remove use of PCI_ERR flag and use
PFLG_DISCONNECTED flag during error condition.

Signed-off-by: Sawan Chandak <sawan.chandak@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>