powerpc, 5xxx, 512x: remove support for mpc5xxx and mpc512x

There was for long time no activity in the mpx5xxx area.
We need to go further and convert to Kconfig, but it
turned out, nobody is interested anymore in mpc5xxx,
so remove it.

Signed-off-by: Heiko Schocher <hs@denx.de>
diff --git a/drivers/input/keyboard.c b/drivers/input/keyboard.c
index 7af5868..84ee015 100644
--- a/drivers/input/keyboard.c
+++ b/drivers/input/keyboard.c
@@ -20,7 +20,7 @@
 
 static int kbd_read_keys(struct input_config *config)
 {
-#if defined(CONFIG_MPC5xxx) || defined(CONFIG_ARCH_MPC8540) || \
+#if defined(CONFIG_ARCH_MPC8540) || \
 		defined(CONFIG_ARCH_MPC8541) || defined(CONFIG_ARCH_MPC8555)
 	/* no ISR is used, so received chars must be polled */
 	ps2ser_check();