gpio: move mpc8xxx/512x gpio driver to drivers/gpio

Move the driver to the place where it is expected to be nowadays. Also
rename its CONFIG-name to match the rest and adapt the defconfigs.
Finally, move selection of REQUIRE_GPIOLIB or WANTS_OPTIONAL_GPIOLIB to
the platforms, because this option is per-platform and not per-driver.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Anatolij Gustschin <agust@denx.de>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Anatolij Gustschin <agust@denx.de>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index d539efd..4744cf2 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -103,6 +103,14 @@
 	def_bool y
 	depends on PPC_MPC52xx
 
+config GPIO_MPC8XXX
+	bool "MPC512x/MPC8xxx GPIO support"
+	depends on PPC_MPC512x || PPC_MPC831x || PPC_MPC834x || PPC_MPC837x || \
+		   FSL_SOC_BOOKE || PPC_86xx
+	help
+	  Say Y here if you're going to use hardware that connects to the
+	  MPC512x/831x/834x/837x/8572/8610 GPIOs.
+
 config GPIO_MSM_V1
 	tristate "Qualcomm MSM GPIO v1"
 	depends on GPIOLIB && ARCH_MSM