MIPS: TX49xx: Rename ARCH_KMALLOC_MINALIGN to ARCH_DMA_MINALIGN

MIPS: TX49xx: Rename ARCH_KMALLOC_MINALIGN to ARCH_DMA_MINALIGN

Architectures need to set ARCH_DMA_MINALIGN to the minimum DMA
alignment (commit a6eb9fe105d5de0053b261148cee56c94b4720ca). Defining
ARCH_KMALLOC_MINALIGN doesn't work anymore.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: anemo@mba.ocn.ne.jp
Patchwork: https://patchwork.linux-mips.org/patch/1544/
Acked-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>