ARM: mxs: enable flexcan on imx28

As the flexcan driver has DT binding for some time now. This patch makes
the flexcan driver available in the can drivers menu if a SOC with flexcan
is enabled.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
diff --git a/arch/arm/mach-mxs/Kconfig b/arch/arm/mach-mxs/Kconfig
index 91cf062..ccdf83b 100644
--- a/arch/arm/mach-mxs/Kconfig
+++ b/arch/arm/mach-mxs/Kconfig
@@ -16,6 +16,7 @@
 	bool
 	select ARM_AMBA
 	select CPU_ARM926T
+	select HAVE_CAN_FLEXCAN if CAN
 	select HAVE_PWM
 	select PINCTRL_IMX28