pinctrl: bcm281xx: make Kconfig dependency more strict

This driver is only useful on BCM281xx, so let the driver depend on
ARCH_BCM_MOBILE but allow compile coverage testing.
The main benefit is that the driver isn't available to be selected for
machines that don't have the matching hardware.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Sherman Yin <syin@broadcom.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/Kconfig

@@ -86,7 +86,7 @@ config PINCTRL_BCM2835
 
 config PINCTRL_BCM281XX
 	bool "Broadcom BCM281xx pinctrl driver"
-	depends on OF
+	depends on OF && (ARCH_BCM_MOBILE || COMPILE_TEST)
 	select PINMUX
 	select PINCONF
 	select GENERIC_PINCONF