sys/auto_init/can: use shared auto_init makefile

sys/auto_init/can/Makefile

@@ -1,3 +1,3 @@
 MODULE = auto_init_can
 
-include $(RIOTBASE)/Makefile.base
+include $(RIOTMAKE)/auto_init.inc.mk

sys/auto_init/can/auto_init_can_linux.c

@@ -16,7 +16,6 @@
  * @}
  */
 
-#ifdef MODULE_CAN_LINUX
 #include "can/device.h"
 #include "candev_linux_params.h"
 
@@ -52,6 +51,3 @@ void auto_init_can_native(void) {
                         candev_linux_params[i].name, &candev_dev_linux[i]);
     }
 }
-#else
-typedef int dont_be_pedantic;
-#endif

sys/auto_init/can/auto_init_periph_can.c

@@ -16,7 +16,6 @@
  * @}
  */
 
-#ifdef MODULE_PERIPH_CAN
 #include "can/device.h"
 #include "can_params.h"
 
@@ -52,6 +51,3 @@ void auto_init_periph_can(void) {
                         candev_params[i].name, &candev_dev[i]);
     }
 }
-#else
-typedef int dont_be_pedantic;
-#endif