Added missing DMA  functions

...6dad3c56477ab066c999

Linux revision https://github.com/torvalds/linux/commit/64ccc9c033c6089b2d426dad3c56477ab066c999 changed dma functions. This seemed to be partially backported in the 3.5.7-ipipe to raspberry pi patch, but not completely, causing compilation to fail if snd-pcm is enabled. The changes attached should fix this.