dmaenegine: edma: fix sparse warnings

this patch fixes following sparse warnings:

edma.c:537:32: warning: symbol 'edma_prep_dma_memcpy' was not declared. Should it be static?
edma.c:1070:6: warning: symbol 'edma_filter_fn' was not declared. Should it be static?
Signed-off-by: NLad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: NVinod Koul <vinod.koul@intel.com>

drivers/dma/edma.c

@@ -15,6 +15,7 @@
 
 #include <linux/dmaengine.h>
 #include <linux/dma-mapping.h>
+#include <linux/edma.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
@@ -534,7 +535,7 @@ static struct dma_async_tx_descriptor *edma_prep_slave_sg(
 	return vchan_tx_prep(&echan->vchan, &edesc->vdesc, tx_flags);
 }
 
-struct dma_async_tx_descriptor *edma_prep_dma_memcpy(
+static struct dma_async_tx_descriptor *edma_prep_dma_memcpy(
 	struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
 	size_t len, unsigned long tx_flags)
 {