powerpc: Simplify push_end definition in pci_32.c

The push_end macro in arch/powerpc/kernel/pci_32.c uses integer
division and multiplication to achieve the effect of rounding a
resource end address up and then advancing it to the end of a
power-of-2 sized region.  This changes it to an equivalent computation
that only needs an integer add and OR.  This is partly based on an
earlier patch by Mel Gorman.
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/pci_32.c

@@ -1113,9 +1113,10 @@ check_for_io_childs(struct pci_bus *bus, struct resource* res, int *found_vga)
 	int	i;
 	int	rc = 0;
 
-#define push_end(res, size) do { unsigned long __sz = (size) ; \
-	res->end = ((res->end + __sz) / (__sz + 1)) * (__sz + 1) + __sz; \
-    } while (0)
+#define push_end(res, mask) do {		\
+	BUG_ON((mask+1) & mask);		\
+	res->end = (res->end + mask) | mask;	\
+} while (0)
 
 	list_for_each_entry(dev, &bus->devices, bus_list) {
 		u16 class = dev->class >> 8;