gpio: ts4800: Add IMX51 dependency

The TS-4800 is an i.MX515 board. Its GPIO driver should only be compiled
for this CPU or for test builds.
Signed-off-by: NJulien Grossholtz <julien.grossholtz@savoirfairelinux.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/gpio/Kconfig

@@ -395,6 +395,7 @@ config GPIO_TB10X
 config GPIO_TS4800
 	tristate "TS-4800 DIO blocks and compatibles"
 	depends on OF_GPIO
+	depends on SOC_IMX51 || COMPILE_TEST
 	select GPIO_GENERIC
 	help
 	  This driver support TS-4800 FPGA GPIO controllers.