powerpc: Make prom_init.c suitable for both 32-bit and 64-bit

Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/prom_init.c

@@ -1968,9 +1968,9 @@ unsigned long __init prom_init(unsigned long r3, unsigned long r4,
 	extern char _stext[];
 	unsigned long hdr;
 	u32 getprop_rval;
+	unsigned long offset = reloc_offset();
 
 #ifdef CONFIG_PPC32
-	unsigned long offset = reloc_offset();
 	reloc_got2(offset);
 #endif