pwm: Kconfig: Enable pwm-tiecap to be built for Keystone

66AK2G SoC has ECAP subsystem that is used as pwm-backlight provider for
display. Hence, enable pwm-tiecap driver to be built for Keystone
architecture.
Signed-off-by: NVignesh R <vigneshr@ti.com>
Signed-off-by: NThierry Reding <thierry.reding@gmail.com>

drivers/pwm/Kconfig

@@ -446,7 +446,7 @@ config PWM_TEGRA
 
 config  PWM_TIECAP
 	tristate "ECAP PWM support"
-	depends on ARCH_OMAP2PLUS || ARCH_DAVINCI_DA8XX
+	depends on ARCH_OMAP2PLUS || ARCH_DAVINCI_DA8XX || ARCH_KEYSTONE
 	help
 	  PWM driver support for the ECAP APWM controller found on AM33XX
 	  TI SOC