Eliminate some warnings

arch/arm/src/sam34/sam_rtt.c

@@ -619,6 +619,7 @@ static int sam34_ioctl(FAR struct timer_lowerhalf_s *lower, int cmd,
 
   DEBUGASSERT(priv);
   rttvdbg("Entry: cmd=%d arg=%ld\n", cmd, arg);
+  UNUSED(priv);
 
   return ret;
 }

arch/arm/src/sam34/sam_tc.c

@@ -572,6 +572,7 @@ static int sam34_ioctl(FAR struct timer_lowerhalf_s *lower, int cmd,
 
   DEBUGASSERT(priv);
   tcvdbg("Entry: cmd=%d arg=%ld\n", cmd, arg);
+  UNUSED(priv);
 
   return ret;
 }

arch/arm/src/sam34/sam_wdt.c

@@ -384,10 +384,7 @@ static int sam34_stop(FAR struct watchdog_lowerhalf_s *lower)
 
 static int sam34_keepalive(FAR struct watchdog_lowerhalf_s *lower)
 {
-  FAR struct sam34_lowerhalf_s *priv = (FAR struct sam34_lowerhalf_s *)lower;
-
   wdvdbg("Entry\n");
-  DEBUGASSERT(priv);
   
   sam34_putreg((WDT_CR_KEY | WDT_CR_WDRSTT), SAM_WDT_CR);
   return OK;