OPNSense/src dc1a6e6sys/dev/ixl if_ixl.c ixl.h, sys/dev/netmap if_ixl_netmap.h

ixl: remove unnecessary limitations related to netmap

Netmap supports the case where TX rings and RX rings have different size.
Remove unnecessary limitations related to netmap support, making the code
simpler.
Also, check that the value of the hw head index written back from the NIC
is valid.

Reviewed by:    erj
Differential Revision:  https://reviews.freebsd.org/D18984
DeltaFile
+6-8sys/dev/netmap/if_ixl_netmap.h
+1-7sys/dev/ixl/if_ixl.c
+0-3sys/dev/ixl/ixl.h
+1-1sys/dev/ixl/ixl_txrx.c
+8-194 files

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