gpio: GPIO_MVEBU should not default to y when compile-testing

Merely enabling compile-testing should not enable additional
functionality.

Fixes: 956ee0c5c969c9ca ("gpio: mvebu: allow building the module with COMPILE_TEST=y")
Signed-off-by: Geert Uytterhoeven <[e-mail]>
Link: https://lore.kernel.org/r/6b9e5[e-mail]
Signed-off-by: Bartosz Golaszewski <[e-mail]>

drivers/gpio/Kconfig

···
 	  Say yes here to support the Mediatek MT7621 SoC GPIO device.
 
 config GPIO_MVEBU
-	def_bool y
+	bool "Marvell Orion and EBU GPIO support" if COMPILE_TEST
 	depends on PLAT_ORION || ARCH_MVEBU || COMPILE_TEST
+	default PLAT_ORION || ARCH_MVEBU
 	select GENERIC_IRQ_CHIP
 	select REGMAP_MMIO