irqchip/imx: IMX_INTMUX should not default to y, unconditionally

Merely enabling CONFIG_COMPILE_TEST should not enable additional code.
To fix this, restrict the automatic enabling of IMX_INTMUX to ARCH_MXC,
and ask the user in case of compile-testing.

Fixes: 66968d7d ("irqchip: Add COMPILE_TEST support for IMX_INTMUX")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210208145605.422943-1-geert+renesas@glider.be

drivers/irqchip/Kconfig

@@ -452,7 +452,8 @@ config IMX_IRQSTEER
 	  Support for the i.MX IRQSTEER interrupt multiplexer/remapper.
 
 config IMX_INTMUX
-	def_bool y if ARCH_MXC || COMPILE_TEST
+	bool "i.MX INTMUX support" if COMPILE_TEST
+	default y if ARCH_MXC
 	select IRQ_DOMAIN
 	help
 	  Support for the i.MX INTMUX interrupt multiplexer.