[PATCH] usb: gadget: u_serial: fix coverity warning: negative index at array

[Macpaul Lin <macpaul.lin@xxxxxxxxxxxx>]

This issue has been reported by coverity scanner.
Replace "int portnum" by "unsigned int", this void negative index at
array.

Signed-off-by: Stan Lu <stan.lu@xxxxxxxxxxxx>
Signed-off-by: Macpaul Lin <macpaul.lin@xxxxxxxxxxxx>
---
 drivers/usb/gadget/function/u_serial.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 8167d37..53951f2 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -587,7 +587,7 @@ static int gs_start_io(struct gs_port *port)
  */
 static int gs_open(struct tty_struct *tty, struct file *file)
 {
-	int		port_num = tty->index;
+	unsigned int	port_num = tty->index;
 	struct gs_port	*port;
 	int		status = 0;
 
@@ -1211,7 +1211,7 @@ int gserial_alloc_line_no_console(unsigned char *line_num)
 	struct gs_port			*port;
 	struct device			*tty_dev;
 	int				ret;
-	int				port_num;
+	unsigned int			port_num;
 
 	coding.dwDTERate = cpu_to_le32(9600);
 	coding.bCharFormat = 8;
-- 
1.7.9.5