Rather than checking the MMU status in every instance of addruart, do it
once in kernel/debug.S, and change the existing addruart macros to
return both physical and virtual addresses. The main debug code can then
select the appropriate address to use.

This will also allow us to retreive the address of a uart for the MMU
state that we're not current in.

Updated with fixes for OMAP from Jason Wang <jason77.wang@gmail.com>
and Tony Lindgren <tony@atomide.com>, and fix for versatile express from
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>.
Signed-off-by: NJeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: NJason Wang <jason77.wang@gmail.com>
Signed-off-by: NTony Lindgren <tony@atomide.com>
Tested-by: NKevin Hilman <khilman@deeprootsystems.com>