linux-wandboard

9p: transport API reorganization

This merges the mux.c (including the connection interface) with trans_fd
in preparation for transport API changes.  Ultimately, trans_fd will need
to be rewritten to clean it up and simplify the implementation, but this
reorganization is viewed as the first step.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>