Fix VSE view clamping not working

Clamping was set up, but `v2d->cur` was never actually modified.

source/blender/editors/space_sequencer/space_sequencer.c

@@ -600,6 +600,8 @@ static void sequencer_main_clamp_view(const bContext *C, ARegion *region)
     view_clamped.ymin = strip_boundbox.ymin;
     view_clamped.ymax = min_ff(strip_boundbox.ymax, strip_boundbox.ymin + range_y);
   }
+
+  v2d->cur = view_clamped;
 }
 
 static void sequencer_main_region_clamp_custom_set(const bContext *C, ARegion *region)