gpio/Kconfig: Fix X86 arch name

X86 Kconfig symbol is X86, not ARCH_X86.

Fixes: c586b3075d5b47d8 (gpio/xilinx: Add support for X86 Arch)
Reported-by: NPaul Bolle <pebolle@tiscali.nl>
Signed-off-by: NRicardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/gpio/Kconfig

@@ -369,7 +369,7 @@ config GPIO_XGENE
 
 config GPIO_XILINX
 	tristate "Xilinx GPIO support"
-	depends on OF_GPIO && (PPC_OF || MICROBLAZE || ARCH_ZYNQ || ARCH_X86)
+	depends on OF_GPIO && (PPC_OF || MICROBLAZE || ARCH_ZYNQ || X86)
 	help
 	  Say yes here to support the Xilinx FPGA GPIO device