ppc/ppc4xx: Convert printfs()

Use a QEMU log primitive for errors and trace events for debug.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: David Gibson <david@gibson.drobear.id.au>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211222064025.1541490-3-clg@kaod.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20220103063441.3424853-4-clg@kaod.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>