misc: mic: SCIF messaging and node enumeration APIs

SCIF messaging APIs which allow sending messages between the SCIF
endpoints via a byte stream based ring buffer which has been
optimized to avoid reads across PCIe. The SCIF messaging APIs
are typically used for short < 1024 byte messages for best
performance while the RDMA APIs which will be submitted in a future
patch series is recommended for larger transfers. The node
enumeration API enables a user to query for the number of nodes
online in the SCIF network and their node ids.

Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Nikhil Rao <nikhil.rao@intel.com>
Signed-off-by: Sudeep Dutt <sudeep.dutt@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>