misc: fastrpc: fix incorrect usage of dma_map_sgtable

dma_map_sgtable() returns 0 on success, which is the opposite of what this
code was doing.

Fixes: 7cd7edb894 ("misc: fastrpc: fix common struct sg_table related issues")
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Link: https://lore.kernel.org/r/20210208200401.31100-1-jonathan@marek.ca
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/fastrpc.c

@@ -520,12 +520,13 @@ fastrpc_map_dma_buf(struct dma_buf_attachment *attachment,
 {
 	struct fastrpc_dma_buf_attachment *a = attachment->priv;
 	struct sg_table *table;
+	int ret;
 
 	table = &a->sgt;
 
-	if (!dma_map_sgtable(attachment->dev, table, dir, 0))
-		return ERR_PTR(-ENOMEM);
-
+	ret = dma_map_sgtable(attachment->dev, table, dir, 0);
+	if (ret)
+		table = ERR_PTR(ret);
 	return table;
 }