MIPS: BMIPS: Rewrite DMA code to use "dma-ranges" property

MIPS: BMIPS: Rewrite DMA code to use "dma-ranges" property

This is a more standardized way of handling DMA remapping, and it is
suitable for the memory map found on BCM3384.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: f.fainelli@gmail.com
Cc: jaedon.shin@gmail.com
Cc: abrestic@chromium.org
Cc: tglx@linutronix.de
Cc: jason@lakedaemon.net
Cc: jogo@openwrt.org
Cc: arnd@arndb.de
Cc: computersforpeace@gmail.com
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8850/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>