Give the kernel more room

My self-built PPC kernel doesn't fit in the region reserved for
the kernel, so I can't use -kernel with it.

Let's just extend the region.
Signed-off-by: NAlexander Graf <agraf@suse.de>

hw/ppc_mac.h

@@ -36,8 +36,8 @@
 #define PROM_ADDR         0xfff00000
 
 #define KERNEL_LOAD_ADDR 0x01000000
-#define CMDLINE_ADDR     0x017ff000
-#define INITRD_LOAD_ADDR 0x01800000
+#define CMDLINE_ADDR     0x027ff000
+#define INITRD_LOAD_ADDR 0x02800000
 
 #define ESCC_CLOCK 3686400