stmmac: move the dma out from the main

This patch moves the dma related functions (interrupt, start, stop etc.)
out from the main driver code. This will help to support new DMA
engines.

Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
8 files changed