IB/ipath: support for userspace apps using core driver

These files introduce a char device that userspace apps use to gain
direct memory-mapped access to the InfiniPath hardware, and routines for
pinning and unpinning user memory in cases where the hardware needs to
DMA into the user address space.

Signed-off-by: Bryan O'Sullivan <bos@pathscale.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>