ARM: pxa/am200epd: fix leak in am200_init_gpio_regs error path

If gpio_request fails when i > 0, gpios[0] is not freed in current
implementation.
Signed-off-by: NAxel Lin <axel.lin@gmail.com>
Signed-off-by: NEric Miao <eric.y.miao@gmail.com>

arch/arm/mach-pxa/am200epd.c

@@ -128,8 +128,8 @@ static int am200_init_gpio_regs(struct metronomefb_par *par)
 	return 0;
 
 err_req_gpio:
-	while (i > 0)
-		gpio_free(gpios[i--]);
+	while (--i >= 0)
+		gpio_free(gpios[i]);
 
 	return err;
 }