misc: fastrpc: prevent memory leak in fastrpc_dma_buf_attach

In fastrpc_dma_buf_attach if dma_get_sgtable fails the allocated memory
for a should be released.
Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
Link: https://lore.kernel.org/r/20190925152742.16258-1-navid.emamdoost@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/fastrpc.c

@@ -527,6 +527,7 @@ static int fastrpc_dma_buf_attach(struct dma_buf *dmabuf,
 			      FASTRPC_PHYS(buffer->phys), buffer->size);
 	if (ret < 0) {
 		dev_err(buffer->dev, "failed to get scatterlist from DMA API\n");
+		kfree(a);
 		return -EINVAL;
 	}