x86, mm: Enable ARCH_DMA_ADDR_T_64BIT with X86_64 || HIGHMEM64G

Set CONFIG_ARCH_DMA_ADDR_T_64BIT when we set dma_addr_t to 64 bits in
<asm/types.h>; this allows Kconfig decisions based on this property.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
LKML-Reference: <201010202255.o9KMtZXu009370@imap1.linux-foundation.org>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>