spi: signedness bug in qspi_trigger_transfer_out_int()

We need "ret" to be unsigned for the error handling to work.  The
signedness of "i" and "n" don't matter but qspi_set_send_trigger()
returns an int so I've changed them to int as well.

Fixes: 4b6fe3edcb ('spi: Using Trigger number to transmit/receive data')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-rspi.c

@@ -727,7 +727,7 @@ static int rspi_rz_transfer_one(struct spi_master *master,
 static int qspi_trigger_transfer_out_int(struct rspi_data *rspi, const u8 *tx,
 					u8 *rx, unsigned int len)
 {
-	unsigned int i, n, ret;
+	int i, n, ret;
 	int error;
 
 	while (len > 0) {