REORG: mux-h1: extract flags and enums into mux_h1-t.h

The same was performed for the H2 multiplexer. H1C and H1S flags are moved
in a dedicated header file. It will be mainly used to be able to decode
mux-h1 flags from the flags utility.

In this patch, we only move the flags to mux_h1-t.h.
2 files changed