scsi: lpfc: Enhance congestion statistics collection

Various improvements are made for collecting congestion statistics:

 - Pre-existing logic is replaced with use of an hrtimer for increased
   reporting accuracy.

 - Congestion timestamp information is reorganized into a single struct.

 - Common statistic collection logic is refactored into a helper routine.

Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Link: https://lore.kernel.org/r/20230523183206.7728-8-justintee8345@gmail.com


Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>