devicestate: Make ast_devstate_changed_literal() return value and doxygen consistent.

Nothing actually cares about the value anyway.

(closes issue ASTERISK-23178)
Reported by: Jonathan Rose
........

Merged revisions 407337 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@407338 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/devicestate.h

@@ -129,7 +129,6 @@ enum ast_device_state ast_parse_device_state(const char *device);
  * active channels list for the device.
  *
  * \retval an AST_DEVICE_??? state
- * \retval -1 on failure
  */
 enum ast_device_state ast_device_state(const char *device);
 

main/devicestate.c

@@ -505,7 +505,7 @@ int ast_devstate_changed_literal(enum ast_device_state state, enum ast_devstate_
 		AST_LIST_UNLOCK(&state_changes);
 	}
 
-	return 1;
+	return 0;
 }
 
 int ast_device_state_changed_literal(const char *dev)