Android.mk: fix compilation of can-calc-bit-timing

Fixes: 9c38c16 ("can-calc-bit-timing: move into subdir")
Reported-by: Tompee Balauag <tompee26@gmail.com>
Link: #373
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Android.mk

@@ -181,7 +181,7 @@ include $(BUILD_EXECUTABLE)
 
 include $(CLEAR_VARS)
 
-LOCAL_SRC_FILES := can-calc-bit-timing.c
+LOCAL_SRC_FILES := calc-bit-timing/can-calc-bit-timing.c
 LOCAL_MODULE := can-calc-bit-timing
 LOCAL_MODULE_TAGS := optional
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/include/