Fix issue clearing issue with multiple cameras

com.unity.render-pipelines.lightweight/LWRP/Passes/ForwardLitPass.cs

             // We need to handle viewport on a RT. We do it by rendering a fullscreen quad + viewport
             if (colorAttachmentHandle != -1 && !cameraData.isDefaultViewport)
             {
-                SetRenderTarget(cmd, BuiltinRenderTextureType.CameraTarget, RenderBufferLoadAction.DontCare, RenderBufferStoreAction.Store, ClearFlag.All, Color.black);
+                SetRenderTarget(cmd, BuiltinRenderTextureType.CameraTarget, RenderBufferLoadAction.DontCare, RenderBufferStoreAction.Store, ClearFlag.None, Color.black);
-                
             }
             else
             {