gpu: host1x: Reset max value when freeing a syncpoint

With job recovery becoming optional, syncpoints may have a mismatch
between their value and max value when freed. As such, when freeing,
set the max value to the current value of the syncpoint so that it
is in a sane state for the next user.

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