Make source pruning configurable via ethtool

[krokodilerian]

As visible in https://github.com/intel/ethernet-linux-ice/blob/main/src/ice_lib.c#L1320, the source pruning is enabled by default in the NICs, and there doesn't seem to be an option to disable it, like the one in i40e. The disabling of source pruning is required if someone wants to run an active-backup bond with arp_validate=all (i.e. to validate both the active and backup links), as the linux bond's detection of the availability of the backup link relies on receiving the packets sent from the same node via the active port. The bond also sets the MACs of both ports to the same one, so source pruning drops these packets.

So it'd be nice if there's a way (probably as in i40e, an ethtool option) to disable source pruning.

p.s. does this need to be submitted separately for the upstream kernel driver?