m68k/mm: m54xx - Add missing initialization of max_pfn

If max_pfn is not initialized, the various /proc/kpage* files are empty,
and selftests/vm/mlock2-tests will fail. max_pfn is also used by the
block layer to calculate DMA masks.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Greg Ungerer <gerg@uclinux.org>
Tested-by: Greg Ungerer <gerg@uclinux.org>

arch/m68k/coldfire/m54xx.c

@@ -98,7 +98,7 @@ static void __init mcf54xx_bootmem_alloc(void)
 	memstart = PAGE_ALIGN(_ramstart);
 	min_low_pfn = PFN_DOWN(_rambase);
 	start_pfn = PFN_DOWN(memstart);
-	max_low_pfn = PFN_DOWN(_ramend);
+	max_pfn = max_low_pfn = PFN_DOWN(_ramend);
 	high_memory = (void *)_ramend;
 
 	m68k_virt_to_node_shift = fls(_ramend - _rambase - 1) - 6;