scsi: fc: Update documentation of sysfs nodes for FPIN stats

Update documentation for sysfs nodes within:

       /sys/class/fc_host
       /sys/class/fc_remote_ports

Link: https://lore.kernel.org/r/20201021092715.22669-6-njavali@marvell.comReviewed-by: NJames Smart <james.smart@broadcom.com>
Reviewed-by: NHimanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: NShyam Sundar <ssundar@marvell.com>
Signed-off-by: NNilesh Javali <njavali@marvell.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Documentation/ABI/testing/sysfs-class-fc_host

+What:		/sys/class/fc_host/hostX/statistics/fpin_cn_yyy
+Date:		July 2020
+Contact:	Shyam Sundar <ssundar@marvell.com>
+Description:
+		These files contain the number of congestion notification
+		events recorded by the F_Port, reported using fabric
+		performance impact notification (FPIN) event.
+
+What:		/sys/class/fc_host/hostX/statistics/fpin_li_yyy
+Date:		July 2020
+Contact:	Shyam Sundar <ssundar@marvell.com>
+Description:
+		These files contain the number of link integrity error
+		events recorded by the F_Port/Nx_Port, reported using fabric
+		performance impact notification (FPIN) event.
+
+What:		/sys/class/fc_host/hostX/statistics/fpin_dn_yyy
+Date:		July 2020
+Contact:	Shyam Sundar <ssundar@marvell.com>
+Description:
+		These files contain the number of delivery related errors
+		recorded by the F_Port/Nx_Port, reported using fabric
+		performance impact notification (FPIN) event.

Documentation/ABI/testing/sysfs-class-fc_remote_ports

+What:		/sys/class/fc_remote_ports/rport-X:Y-Z/statistics/fpin_cn_yyy
+Date:		July 2020
+Contact:	Shyam Sundar <ssundar@marvell.com>
+Description:
+		These files contain the number of congestion notification
+		events recorded by the F_Port/Nx_Port, reported using fabric
+		performance impact notification (FPIN) event.
+
+What:		/sys/class/fc_remote_ports/rport-X:Y-Z/statistics/fpin_li_yyy
+Date:		July 2020
+Contact:	Shyam Sundar <ssundar@marvell.com>
+Description:
+		These files contain the number of link integrity error
+		events recorded by the F_Port/Nx_Port, reported using fabric
+		performance impact notification (FPIN) event.
+
+What:		/sys/class/fc_remote_ports/rport-X:Y-Z/statistics/fpin_dn_yyy
+Date:		July 2020
+Contact:	Shyam Sundar <ssundar@marvell.com>
+Description:
+		These files contain the number of delivery related errors
+		recorded by the F_Port/Nx_Port, reported using fabric
+		performance impact notification (FPIN) event.