Reduce the number of IASetInputLayout calls to 1 in all cases and set the
fewest number of buffers at once.

BUG=260069

Change-Id: I059337fc6601ecefd801ef37546935becaa0d355
Reviewed-on: https://chromium-review.googlesource.com/199345Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>