gpu: host1x: Fix memory access in syncpt request

This patch fixes a bad memory access in syncpoint request code. If
no syncpoints were available, the code accessed unreserved memory
area causing unexpected behaviour.

Signed-off-by: Arto Merilainen <amerilainen@nvidia.com>
Acked-By: Terje Bergstrom <tbergstrom@nvidia.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>