char: remove unused qemu_chr_fe_event

char: remove unused qemu_chr_fe_event

I introduced this function in d61b0c9a2f7f, but it isn't
used. Furthermore, it was incomplete, as it would need to translate QEMU
chr events to Spice port events.

(presumably it was used in the follow-up NBD-spice series that was not
completed: http://lists.gnu.org/archive/html/qemu-devel/2013-11/msg02024.html)

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20161022100951.19562-4-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>