scsi: lpfc: Add auto EQ delay logic

Administrator intervention is currently required to get good numbers
when switching from running latency tests to IOPS tests.

The configured interrupt coalescing values will greatly effect the
results of these tests.  Currently, the driver has a single coalescing
value set by values of the module attribute.  This patch changes the
driver to support auto-configuration of the coalescing value based on
the total number of outstanding IOs and average number of CQEs processed
per interrupt for an EQ.  Values are checked every 5 seconds.

The driver defaults to the automatic selection. Automatic selection can
be disabled by the new lpfc_auto_imax module_parameter.

Older hardware can only change interrupt coalescing by mailbox
command. Newer hardware supports change via a register. The patch
support both.

Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>