nvc0: set rsvd_kick correctly

This prevents trampling beyond the end of the command stream during flushes.

NOTE: This is a candidate for the stable branches.

Reported-by: Christoph Bumiller <christoph.bumiller@speed.at>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
nine: locking for D3DCREATE_MULTITHREADED

That is for buggy applications that fail at doing synchronization
themselves. We need to lock everything for them.