[PATCH] ppc64: Make udbg_init_uart set the ppc_md udbg methods.

make udbg_init_uart set the ppc_md udbg methods.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>