powerpc: Fix find_next_bit on 32-bit

We had a "64" that didn't get changed to BITS_PER_LONG, resulting
in find_next_bit not working correctly.

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/lib/bitops.c b/arch/powerpc/lib/bitops.c
index b67ce30..f68ad71 100644
--- a/arch/powerpc/lib/bitops.c
+++ b/arch/powerpc/lib/bitops.c
@@ -41,7 +41,7 @@
 	tmp = *p;
 
 found_first:
-	tmp &= (~0UL >> (64 - size));
+	tmp &= (~0UL >> (BITS_PER_LONG - size));
 	if (tmp == 0UL)		/* Are any bits set? */
 		return result + size;	/* Nope. */
 found_middle: