remove _IO_BASE and KSEG1ADDR from board configuration files

remove _IO_BASE and KSEG1ADDR from board configuration files

The KSEG1ADDR macro used to be necessary for the RTL8139 Ethernet
driver, but the code that used that macro was removed over a year
ago, so board configuration files no longer need to define it.

The _IO_BASE macro is also automatically defined to 0 if it isn't
already set, so there's no need to define that macro either in the
board configuration files.

Signed-off-by: Timur Tabi <[email protected]>
Acked-by: Nobuhiro Iwamatsu <[email protected]>
Acked-by: Andy Fleming <[email protected]>
Acked-by: Andre Schwarz <[email protected]>
Acked-by: Kim Phillips <[email protected]>