spi: return error if kmap'd buffers passed to spi_map_buf()

Current spi_map_buf() implementation supports creates sg_table for
vmalloc'd and kmalloc'd buffers. Therefore return error if kmap'd buffer
(or any other buffer) is passed to spi_map_buf().
Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi.c

@@ -717,9 +717,11 @@ static int spi_map_buf(struct spi_master *master, struct device *dev,
 	if (vmalloced_buf) {
 		desc_len = min_t(int, max_seg_size, PAGE_SIZE);
 		sgs = DIV_ROUND_UP(len + offset_in_page(buf), desc_len);
-	} else {
+	} else if (virt_addr_valid(buf)) {
 		desc_len = min_t(int, max_seg_size, master->max_dma_len);
 		sgs = DIV_ROUND_UP(len, desc_len);
+	} else {
+		return -EINVAL;
 	}
 
 	ret = sg_alloc_table(sgt, sgs, GFP_KERNEL);