gpu: host1x: Fix syncpoint ID field size on Tegra186

The number of syncpoints on Tegra186 is 576 and therefore no longer fits
into 8 bits. Increase the size of the syncpoint ID field to 10 in order
to accomodate all syncpoints.

Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>