powerpc: Fix bootm to boot up again with a Ramdisk

Commit 2a1a2cb6 didnt remove the dummy mem reservation in fdt_chosen,
and this stopped Linux from booting with a Ramdisk. This patch fixes
this, by deleting the useless dummy mem reservation.

When booting with a Ramdisk, a fix offset FDT_RAMDISK_OVERHEAD is now
added to of_size, so we dont need anymore a dummy mem reservation.

I measured the value of FDT_RAMDISK_OVERHEAD on a MPC8270 based
system (=0x44 bytes) and rounded it up to 0x80).

Signed-off-by: Heiko Schocher <hs@denx.de>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/common/cmd_fdt.c b/common/cmd_fdt.c
index 0593bad..288a5c4 100644
--- a/common/cmd_fdt.c
+++ b/common/cmd_fdt.c
@@ -450,7 +450,8 @@
 			initrd_end = simple_strtoul(argv[3], NULL, 16);
 		}
 
-		fdt_chosen(working_fdt, initrd_start, initrd_end, 1);
+		fdt_chosen(working_fdt, 1);
+		fdt_initrd(working_fdt, initrd_start, initrd_end, 1);
 	}
 	/* resize the fdt */
 	else if (strncmp(argv[1], "re", 2) == 0) {