D3D11: Refactor vertex format tables. Use switch statements based on the format type enum, instead of a map from the old VertexFormat structure to the info payload. This saves on lookup and initialization time. BUG=angleproject:959 Change-Id: I6d1bf282c88f67272ca067cb64bc71e77824a12e Reviewed-on: https://chromium-review.googlesource.com/277290 Tested-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>