Fix a few bugs in the receive state machine. In doing back to tracking

Fix a few bugs in the receive state machine.  In doing back to tracking
whether or not the state machine is enabled rather than tracking the
specific instance of trying to halt the state machine.

dev/ns_gige.cc:
    change back to tracking the state machine's enableness instead of
    whether or not it is trying to halt.  Also fix a major bug that
    would cause the NIC to drop packets when the rx state machine was
    idle, but enabled.
    Fix a couple other bugs in the state machine where the idle interrupt
    would happen at the wrong time.
    Add a warning to deal with improper values of intrTick
dev/ns_gige.hh:
    We need to keep track of whether the state machine is enabled
    or not separately from the control register since the bits don't
    always reflect the truth.

--HG--
extra : convert_revision : 20056b225fa62a0744473babfd693506aa5f29b2