powerpc: fix up for mmu_mapin_ram api change

Today's linux-next build (powerpc ppc44x_defconfig) failed like this:

arch/powerpc/mm/pgtable_32.c: In function 'mapin_ram':
arch/powerpc/mm/pgtable_32.c:318: error: too many arguments to function 'mmu_mapin_ram'

Casued by commit de32400dd2 ("wii: use both
mem1 and mem2 as ram").

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

arch/powerpc/mm/44x_mmu.c

@@ -88,7 +88,7 @@ void __init MMU_init_hw(void)
 	flush_instruction_cache();
 }
 
-unsigned long __init mmu_mapin_ram(void)
+unsigned long __init mmu_mapin_ram(unsigned long top)
 {
 	unsigned long addr;