can: Enable -D__CHECK_ENDIAN__ for sparse by default

This patch enables endian checking by default when running sparse via "make
C=2" for example.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile
index fc93041..c533c62 100644
--- a/drivers/net/can/Makefile
+++ b/drivers/net/can/Makefile
@@ -29,4 +29,5 @@
 obj-$(CONFIG_CAN_RCAR)		+= rcar_can.o
 obj-$(CONFIG_CAN_XILINXCAN)	+= xilinx_can.o
 
-subdir-ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG
+subdir-ccflags-y += -D__CHECK_ENDIAN__
+subdir-ccflags-$(CONFIG_CAN_DEBUG_DEVICES) += -DDEBUG