CLR/HOME support in MEGA65 native mode

src/kernal/screen_m65/mega65_clrscr.s

@@ -113,9 +113,10 @@ m65_clrscr_loop_done:
 
     // FALLTROUGH
 
-m65_home: // XXX reuse
+M65_HOME:
 
-	// XXX provide proper implementation
+	lda M65_SCRWINMODE
+	bmi M65_HOME_winmode
 
 	lda #$00
 	sta M65__TXTROW
@@ -124,3 +125,9 @@ m65_home: // XXX reuse
 	sta M65_TXTROW_OFF+1
 
 	rts
+
+M65_HOME_winmode:
+
+	// XXX provide implementation
+
+	rts