[PATCH] powerpc: fix of_parse_dma_window

My js20 appears to lack the ibm,#dma- properties, and boot fails with a
"Kernel panic - not syncing: iommu_init_table: Can't allocate 0 bytes"
message.

This adds a fallback to the "#address-cells" property in case the
"#ibm,dma-address-cells" property is missing.   Tested on js20 and
power5 lpar.

Unless there is a more elegant solution... :-)
Signed-off-by: Will Schmidt <willschm@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/prom_parse.c

@@ -561,6 +561,9 @@ void of_parse_dma_window(struct device_node *dn, unsigned char *dma_window_prop,
 	*busno = *(dma_window++);
 
 	prop = get_property(dn, "ibm,#dma-address-cells", NULL);
+	if (!prop)
+		prop = get_property(dn, "#address-cells", NULL);
+
 	cells = prop ? *(u32 *)prop : prom_n_addr_cells(dn);
 	*phys = of_read_addr(dma_window, cells);