make tags useful for block drivers and hardaware devices

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Makefile

@@ -301,7 +301,7 @@ test speed: all
 	$(MAKE) -C tests $@
 
 TAGS:
-	etags *.[ch] tests/*.[ch]
+	etags *.[ch] tests/*.[ch] block/*.[ch] hw/*.[ch]
 
 cscope:
 	rm -f ./cscope.*