MFC 267284
Fixes from Fanco Ficthner on transparent mode

• The way rings are updated changed with the last API bump. Also sync ->head when moving slots in netmap_sw_to_nic().

• Remove a crashing selrecord() call.

• Unclog the logic surrounding netmap_rxsync_from_host().

• Add timestamping to RX host ring.

• Remove a couple of obsolete comments.

Submitted by: Franco Fichtner
MFC after: 3 days
Sponsored by: Packetwerk