FKEY_EVENTS cleanups

- Fix a bug where an FKEY_EVENT request would always return EINVAL

 - Replace two manual usage of FKEY_EVENT messages by a call to
   fkey_events which is mapped to fkey_ctl.

Change-Id: I7bc54cade45a29f14c89313b3ec4c28d81a4ec93

drivers/tty/arch/i386/keyboard.c

@@ -501,6 +501,7 @@ message *m_ptr;			/* pointer to the request message */
       }
       break;
   case FKEY_EVENTS:
+      result = OK;			/* everything will be ok*/
       m_ptr->FKEY_FKEYS = m_ptr->FKEY_SFKEYS = 0;
       for (i=0; i < 12; i++) {		/* check (Shift+) F1-F12 keys */
           if (fkey_obs[i].proc_nr == m_ptr->m_source) {