powerpc/prom_init: Fixup missing #size-cells on PowerBook6,7

Similar to the PowerMac3,1, the PowerBook6,7 is missing the #size-cells
property on the i2s node.

Depends-on: commit 045b14c ("of: WARN on deprecated #address-cells/#size-cells handling")
Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
[maddy: added "commit" work in depends-on to avoid checkpatch error]
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/875xmizl6a.fsf@igel.home

Author: andreas-schwab

arch/powerpc/kernel/prom_init.c

@@ -2889,11 +2889,11 @@ static void __init fixup_device_tree_pmac(void)
 	char type[8];
 	phandle node;
 
-	// Some pmacs are missing #size-cells on escc nodes
+	// Some pmacs are missing #size-cells on escc or i2s nodes
 	for (node = 0; prom_next_node(&node); ) {
 		type[0] = '\0';
 		prom_getprop(node, "device_type", type, sizeof(type));
-		if (prom_strcmp(type, "escc"))
+		if (prom_strcmp(type, "escc") && prom_strcmp(type, "i2s"))
 			continue;
 
 		if (prom_getproplen(node, "#size-cells") != PROM_ERROR)