ccid: rename ccid_descriptors.c to ccid_main_functionfs

... which resembles its actual purpose much better

Change-Id: I02d21a9594db8e87714b6ce0d106ed3ef5297548
diff --git a/ccid/Makefile b/ccid/Makefile
index e23823a..317fcbd 100644
--- a/ccid/Makefile
+++ b/ccid/Makefile
@@ -1,10 +1,10 @@
 CFLAGS=-Wall -g
 
-ccid_descriptors: ccid_descriptors.o ccid_proto.o ccid_device.o
+ccid_functionfs: ccid_main_functionfs.o ccid_proto.o ccid_device.o
 	$(CC) $(CFLAGS) -lasan -losmocore -laio -o $@ $^
 
 %.o: %.c
 	$(CC) $(CFLAGS) -o $@ -c $^
 
 clean:
-	rm ccid_descriptors *.o
+	rm ccid_functionfs *.o