powerpc: mpc512x: fix boot breakage

Commit d6b11fd1 (powerpc: remove MBX and MBX860T boards support)
removed mbxbar field in "struct sysconf512x" by mistake and broke
booting on mpc5121 boards. Fix it.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
1 file changed