mambo: Add a reservation for the initramfs

On most systems the initramfs is loaded inside the part of memory
reserved for the OS [0x0-0x30000000] and skiboot will never touch it.
On mambo it's loaded at 0x80000000 and if you're unlucky skiboot can
allocate over the top of it and corrupt the initramfs blob.

There might be the downside that the kernel cannot re-use the initramfs
memory since it's marked as reserved, but the kernel might also free it
anyway.

Fixes: 65612f1
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Tested-by: Michael Ellerman <mpe@ellerman.id.au>
[stewart@linux.vnet.ibm.com: add Fixes]
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

external/mambo/skiboot.tcl

@@ -222,6 +222,11 @@ mysim of addprop $reserved_memory int "#size-cells" 2
 mysim of addprop $reserved_memory int "#address-cells" 2
 mysim of addprop $reserved_memory empty "ranges" ""
 
+set initramfs_res [mysim of addchild $reserved_memory "initramfs" ""]
+set reg [list $cpio_start $cpio_size ]
+mysim of addprop $initramfs_res array64 "reg" reg
+mysim of addprop $initramfs_res empty "name" "initramfs"
+
 set fake_nvram_node [mysim of addchild $reserved_memory "ibm,fake-nvram" ""]
 set reg [list $fake_nvram_start $fake_nvram_size ]
 mysim of addprop $fake_nvram_node array64 "reg" reg