ColdFire: Fix missing _IO_BASE which caused compile error

The compile error was caused by a recent patch. Affected platforms -
M5253DEMO.h, M5253EVBE.h, and M54455EVB.h. Adding the _IO_BASE
automatically defined to 0 in asm-m68k/io.h if it isn't set in
platform configuration file.

Signed-off-by: TsiChung Liew <tsicliew@gmail.com>
1 file changed