nf10-newnic: add helper macros to make it more readable

currently not applied to rx, but tx works
nf10-newnic: split a single rx pointer to prod/cons

But, user-level processing has to be modified, but not yet.
nf10-newnic: in revising xen rx processing (in progress)
nf10-newnic: fix some bugs in nfback
nf10-newnic: Xen RX works with mini-os frontend
- before if frontend lags behind packet forwarding rate from nfback,
  some packets are dropped simply, but with this commit, it is enabled
  to keep the packets, which used to be dropped, in the rx_buf list just
  like original netback keeps skb list, and try to resend the pending
  ones whenever slots become available again.
nf10-newnic: simplify dword increment aligned with qword
nf10-newnic: make lbuf api to be used by driver/user/netfront

initial design of LBUF API
nf10-newnic: some reorganization
first modification to overcome out-of-order delivery of tlp
nf10-newnic: a little change of lbuf api
nf10-newnic: pass needed size to be transferred to Xen frontend

fix a bug in chunking lbuf into smaller chunks that should fit in Xen
ring. Currently, fix the chunk size to 64 pages (512K), but should be
changed to be configurable after some profiling. It currently works with
a modified mini-os frontend.
modified the tx side. tags are handled by one entity. one tag per huge page at a time. requests sizes are variable and as big as possible.
Warning! I haven't tested it yet.
timing meets easily
no longer support for reordering of tlps, but no more than 1 request is issued at the same time.
nf10-newnic: add some debugging code
nf10-newnic: fill grant copy buffer page-by-page
nf10-newnic: misc change for pr_debug
Merge branch 'tx_rx' of https://github.com/myworkbench/InHouse-RDMA into linux_driver-tx_rx
nf10-newnic: add some ndo callbacks as just placeholders (misc)
nf10-newnic: add a placeholder for non-crash in ifconfig w/ ip addr

as soon as ifconfig is up with ip addr, a small packet is sent, but it
has no enough headroom to add netfpga metadata as is. So, it should be
handled by copying the packet to another memory area. Before
implementing this, added a placeholder that returns immediately in the
event of no headroom. But, it's NOT a correct way.