More conversions of ref-counted parameters to references:

More conversions of ref-counted parameters to references:
Statistics::NodePtr, StaticInstPtr, ethernet PacketPtr.

base/statistics.hh:
    Change NodePtr parameters to Nodeptr &.
cpu/exetrace.hh:
    Change StaticInstPtr parameters to StaticInstPtr &.
dev/etherbus.cc:
dev/etherbus.hh:
dev/etherdump.cc:
dev/etherdump.hh:
dev/etherint.hh:
dev/etherlink.cc:
dev/etherlink.hh:
dev/ethertap.cc:
dev/ethertap.hh:
    change PacketPtr parameters to PacketPtr &.

--HG--
extra : convert_revision : a778efdca33b0ec5beb76cf47db0e9e4728897ee