Do not require user to add "-p" to boot arguments to see
early info printed to prom console.

This is similar to the sparc64 functionality - which was added with:
3c62a2d3 ("[SPARC64]: Always register
a PROM based early console.")
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>