[POWERPC] Remove a couple of unused definitions from pgtable_32.c

In arch/powerpc/mm/pgtable_32.c, the variable io_bat_index and the
macro is_power_of_4() no longer have any users.  This removes them.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/mm/pgtable_32.c

@@ -36,7 +36,6 @@
 unsigned long ioremap_base;
 unsigned long ioremap_bot;
 EXPORT_SYMBOL(ioremap_bot);	/* aka VMALLOC_END */
-int io_bat_index;
 
 #if defined(CONFIG_6xx) || defined(CONFIG_POWER3)
 #define HAVE_BATS	1
@@ -299,9 +298,6 @@ void __init mapin_ram(void)
 	}
 }
 
-/* is x a power of 4? */
-#define is_power_of_4(x)	is_power_of_2(x) && (ffs(x) & 1)
-
 /* Scan the real Linux page tables and return a PTE pointer for
  * a virtual address in a context.
  * Returns true (1) if PTE was found, zero otherwise.  The pointer to