We set this signal for debugging purposes, so don't die if it's absent
(such as in a post-synthesis simulation).
Signed-off-by: Sean Anderson <seanga2@gmail.com>
To make sure that pmd.signal_status comes up at the right time, keep
signal_detect low at the start of simulation. We don't need to set
pmd.rx, because X is the default value (or rather Z is, but it's the
same for our purposes).
Fixes: 1d65661 ("Add pmd")
Signed-off-by: Sean Anderson <seanga2@gmail.com>