If we make all UART addressing consistent across all ColdFire family members
then we will be able to remove the duplicated plaform data and use a single
setup for all.

So modify the ColdFire 5206 UART addressing so that:

. UARTs are numbered from 0 up
. base addresses are absolute (not relative to MBAR peripheral register)
. use a common name for IRQs used
Signed-off-by: Greg Ungerer <gerg@uclinux.org>