puzzle: row and col values of 1 are not supported

(cherry picked from commit 05f9c0acdbf2832d507724d644d32aa06c47cf65)

Conflicts:
	modules/video_filter/puzzle.c

modules/video_filter/puzzle.c

@@ -364,11 +364,11 @@ static int PuzzleCallback( vlc_object_t *p_this, char const *psz_var,
     vlc_mutex_lock( &p_sys->lock );
     if( !strcmp( psz_var, CFG_PREFIX "rows" ) )
     {
-        p_sys->change.i_rows = __MAX( 1, newval.i_int );
+        p_sys->change.i_rows = __MAX( 2, newval.i_int );
     }
     else if( !strcmp( psz_var, CFG_PREFIX "cols" ) )
     {
-        p_sys->change.i_cols = __MAX( 1, newval.i_int );
+        p_sys->change.i_cols = __MAX( 2, newval.i_int );
     }
     else if( !strcmp( psz_var, CFG_PREFIX "black-slot" ) )
     {