x86: fix is_io_mapping_possible() build warning on i386 allnoconfig

i386 allnoconfig:

 arch/x86/mm/iomap_32.c: In function 'is_io_mapping_possible':
 arch/x86/mm/iomap_32.c:27: warning: comparison is always false due to limited range of data type

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/mm/iomap_32.c

@@ -23,7 +23,7 @@
 
 int is_io_mapping_possible(resource_size_t base, unsigned long size)
 {
-#ifndef CONFIG_X86_PAE
+#if !defined(CONFIG_X86_PAE) && defined(CONFIG_PHYS_ADDR_T_64BIT)
 	/* There is no way to map greater than 1 << 32 address without PAE */
 	if (base + size > 0x100000000ULL)
 		return 0;