[software] Remove DMA with mode selection

Author: mbertuletti

software/runtime/dma.h

@@ -74,10 +74,4 @@ void dma_memcpy_blocking(void *dest, const void *src, size_t len) {
   dma_wait();
 }
 
-void dma_memcpy_ModeSel(void *dest, const void *src, size_t len,
-                        uint32_t mode_sel) {
-  dma_mode_reg = mode_sel;
-  dma_memcpy_nonblocking(dest, src, len);
-}
-
 #endif // _DMA_H_