dm: powerpc: ppc4xx: Move glacier to use driver model for serial

Adjust Kconfig to default to driver model for glacier, canyonlands and
arches.

Signed-off-by: Simon Glass <sjg@chromium.org>

board/amcc/canyonlands/Kconfig

@@ -29,4 +29,18 @@ config ARCHES
 
 endchoice
 
+config DM
+	default y
+
+config DM_SERIAL
+	default y
+
+config SYS_MALLOC_F
+	bool
+	default y
+
+config SYS_MALLOC_F_LEN
+	hex
+	default 0x400
+
 endif