[POWERPC] Convert from DBG() to pr_debug() in platforms/pseries/

In pseries/lpar.c, fix some printf specifier mismatches, and add
a newline to one printk.

In pseries/rtasd.c add "rtasd" to some messages to make it clear
where they're coming from.

In pseries/scanlog.c remove the hand-rolled runtime debugging support
in there. This file has been largely unchanged for eons, if we need to
debug it in future we can recompile.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>