gpio: do not include <asm/arch/gpio.h> on TARGET_BCMNS3

As no gpio.h is defined for this architecture, to avoid
compilation failure, do not include <asm/arch/gpio.h> for
arch bcmns3.

Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/include/asm/gpio.h b/arch/arm/include/asm/gpio.h
index 7715a01..7dc87af 100644
--- a/arch/arm/include/asm/gpio.h
+++ b/arch/arm/include/asm/gpio.h
@@ -2,7 +2,8 @@
 	!defined(CONFIG_ARCH_K3) && !defined(CONFIG_ARCH_BCM68360) && \
 	!defined(CONFIG_ARCH_BCM6858) && !defined(CONFIG_ARCH_BCM63158) && \
 	!defined(CONFIG_ARCH_ROCKCHIP) && !defined(CONFIG_ARCH_ASPEED) && \
-	!defined(CONFIG_ARCH_U8500) && !defined(CONFIG_CORTINA_PLATFORM)
+	!defined(CONFIG_ARCH_U8500) && !defined(CONFIG_CORTINA_PLATFORM) && \
+	!defined(CONFIG_TARGET_BCMNS3)
 #include <asm/arch/gpio.h>
 #endif
 #include <asm-generic/gpio.h>