linux-phytec-ti

net: prp: add packet handling support

DAN-P nodes are to receive traditional IP packets as well
PRP (Parallel Redundancy Protocol) tagged (trailer) packets.
This patch adds logic to format L2 frames from network
stack to add a trailer and send it as duplicates over the
slave interfaces. At the ingress, it strips the trailer,
do duplicate detection and rejection and forward a stripped
frame up the network stack. Unlike HSR, PRP device should
accept frames from Singly Attached Nodes (SAN) and mark
the link where the frame came from in the node table. As Supervisor
frame LSDU size is same for HSR and PRP, rename the constant for
the same.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>