tpl_vk_wsi_thread: Increased the ref_cnt of swapchain_buffers.

tpl_vk_wsi_thread: Increased the ref_cnt of swapchain_buffers.

 - vulkan-wsi-tizen creates vkImage(s) from the swapchain_buffers obtained
  from the tpl_surface_get_swapchain_buffers() API.

 - If the queue_reset occurs in the event thread, then swapchain_buffers that
  have already been acquired by wsi will be destroyed, which can cause problems.

 - Therefore, even if queue_reset occurs in event_thread,
  TPL must increase ref_cnt of swapchain_buffers so that it is valid
  until swapchain is destroyed.

Change-Id: Ibe41f212a64da89dbc30ea3f137f44dab187eb50
Signed-off-by: Joonbum Ko <joonbum.ko@samsung.com>