pwm: bcm2835: Allow building for ARCH_BRCMSTB

BCM7211 is supported using ARCH_BRCMSTB and uses this PWM controller
driver, make it possible to build it.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/Kconfig

@@ -100,7 +100,7 @@ config PWM_BCM_KONA
 
 config PWM_BCM2835
 	tristate "BCM2835 PWM support"
-	depends on ARCH_BCM2835
+	depends on ARCH_BCM2835 || ARCH_BRCMSTB
 	help
 	  PWM framework driver for BCM2835 controller (Raspberry Pi)