If the serial port gets shut down, then console output stalls.  9 out
of 10 kernel hackers agree, this is a bad thing.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>