sm501: make SerialMM a child, export chardev property

Embed the SerialMM sybus device, and re-export its "chardev" property.
That way, we can get rid of PROP_PTR "chr-state" and better track
devices relationship.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
2 files changed