Fix legacy use of kKHR_swapchain_GrVkExtensionFlag when making GrVkGpu.

Change-Id: I740c1c4832d0a2b8f9f2f5826348f6d65849d14b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/210429
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
1 file changed