spi: match var type to return type of wait_for_completion

return type of wait_for_completion_timeout is unsigned long not int, this
patch changes the type of m from int to unsigned long.
Signed-off-by: NNicholas Mc Guire <der.herr@hofr.at>
Signed-off-by: NMark Brown <broonie@kernel.org>

drivers/spi/spi.c

@@ -788,7 +788,7 @@ static int spi_transfer_one_message(struct spi_master *master,
 	struct spi_transfer *xfer;
 	bool keep_cs = false;
 	int ret = 0;
-	int ms = 1;
+	unsigned long ms = 1;
 
 	spi_set_cs(msg->spi, true);