MIPS: lantiq: pass struct device to DMA API functions

The DMA API generally relies on a struct device to work properly, and
only barely works without one for legacy reasons.  Pass the easily
available struct device from the platform_device to remedy this.

Also use GFP_KERNEL instead of GFP_ATOMIC as the gfp_t for the memory
allocation, as we aren't in interrupt context or under a lock.

Note that this whole function looks somewhat bogus given that we never
even look at the returned dma address, and the CPHYSADDR magic on
a returned noncached mapping looks "interesting".  But I'll leave
that to people more familiar with the code to sort out.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: John Crispin <john@phrozen.org>
Cc: Vinod Koul <vkoul@kernel.org>
Cc: Dmitry Tarnyagin <dmitry.tarnyagin@lockless.no>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: dmaengine@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-usb@vger.kernel.org
Cc: linux-fbdev@vger.kernel.org
Cc: alsa-devel@alsa-project.org
Cc: iommu@lists.linux-foundation.org