imx9: gpio: include types.h header

Include types.h header for u32, following Linux Coding Style to include
necessary headers.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/include/asm/arch-imx9/gpio.h b/arch/arm/include/asm/arch-imx9/gpio.h
index 4073202..ca763f5 100644
--- a/arch/arm/include/asm/arch-imx9/gpio.h
+++ b/arch/arm/include/asm/arch-imx9/gpio.h
@@ -6,6 +6,8 @@
 #ifndef __ASM_ARCH_IMX9_GPIO_H
 #define __ASM_ARCH_IMX9_GPIO_H
 
+#include <linux/types.h>
+
 struct gpio_regs {
 	u32 gpio_pdor;
 	u32 gpio_psor;