net_dma: call dmaengine_get only if NET_DMA enabled

Based upon a patch from Atsushi Nemoto <anemo@mba.ocn.ne.jp>

--------------------
The commit 649274d993212e7c23c0cb734572c2311c200872 ("net_dma:
acquire/release dma channels on ifup/ifdown") added unconditional call
of dmaengine_get() to net_dma.  The API should be called only if
NET_DMA was enabled.
--------------------

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 3e0f64c..3e68469 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -282,6 +282,18 @@
 }
 #endif
 
+#ifdef CONFIG_NET_DMA
+#define net_dmaengine_get()	dmaengine_get()
+#define net_dmaengine_put()	dmaengine_put()
+#else
+static inline void net_dmaengine_get(void)
+{
+}
+static inline void net_dmaengine_put(void)
+{
+}
+#endif
+
 dma_cookie_t dma_async_memcpy_buf_to_buf(struct dma_chan *chan,
 	void *dest, void *src, size_t len);
 dma_cookie_t dma_async_memcpy_buf_to_pg(struct dma_chan *chan,