scsi: lpfc: Convert bootstrap mbx polling from msleep to udelay

Current code is using msleep when polling for hw ready. Unfortunately the
msleep routine isn't very accurate on rescheduling. In fact, on a busy
systems which reset the adapter, it became 10s of seconds before it was
rescheduled.

Fix by busy waiting using udelay. As we're now busy waiting, significantly
reduce the wait time so that we can exit the pool loop as soon as possible.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/lpfc/lpfc_sli.c

@@ -8507,7 +8507,7 @@ lpfc_sli4_wait_bmbx_ready(struct lpfc_hba *phba, LPFC_MBOXQ_t *mboxq)
 		bmbx_reg.word0 = readl(phba->sli4_hba.BMBXregaddr);
 		db_ready = bf_get(lpfc_bmbx_rdy, &bmbx_reg);
 		if (!db_ready)
-			msleep(2);
+			mdelay(2);
 
 		if (time_after(jiffies, timeout))
 			return MBXERR_ERROR;