gpio/xilinx: Add support for X86 Arch

Core can be accessed via PCIe on X86 platform.
This patch also allows the driver to be used as module.

Acked-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/gpio-xilinx.c b/drivers/gpio/gpio-xilinx.c
index c7ed92b..554060a 100644
--- a/drivers/gpio/gpio-xilinx.c
+++ b/drivers/gpio/gpio-xilinx.c
@@ -30,7 +30,7 @@
 #define XGPIO_CHANNEL_OFFSET	0x8
 
 /* Read/Write access to the GPIO registers */
-#ifdef CONFIG_ARCH_ZYNQ
+#if defined(CONFIG_ARCH_ZYNQ) || defined(CONFIG_X86)
 # define xgpio_readreg(offset)		readl(offset)
 # define xgpio_writereg(offset, val)	writel(val, offset)
 #else