This patch adds a basic framework for creating I/O channels
for I/O devices. An spdk_io_channel represents a one-to-one
mapping between a calling thread (represented by spdk_thread)
and an I/O device that the thread will perform I/O operations
on.
Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: I658ab7f995cc962f4e2a204e058cdd3ad3fd735d
