mxc: gpio add i.MX6UL support

i.MX6UL does not have GPIO6/7, so do not include them for i.MX6UL.

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
diff --git a/drivers/gpio/mxc_gpio.c b/drivers/gpio/mxc_gpio.c
index 2012f99..57a650f 100644
--- a/drivers/gpio/mxc_gpio.c
+++ b/drivers/gpio/mxc_gpio.c
@@ -45,11 +45,15 @@
 #endif
 #if defined(CONFIG_MX27) || defined(CONFIG_MX53) || defined(CONFIG_MX6)
 	[4] = GPIO5_BASE_ADDR,
+#ifndef CONFIG_MX6UL
 	[5] = GPIO6_BASE_ADDR,
 #endif
+#endif
 #if defined(CONFIG_MX53) || defined(CONFIG_MX6)
+#ifndef CONFIG_MX6UL
 	[6] = GPIO7_BASE_ADDR,
 #endif
+#endif
 };
 
 static int mxc_gpio_direction(unsigned int gpio,