i965/sync: Rename brw_fence_insert()

i965/sync: Rename brw_fence_insert()

Rename to brw_fence_insert_locked(). This is correct because the fence's
mutex is effectively locked, as all callers are also *creators* of the
fence, and have not yet returned the new fence.

This reduces noise in the next patch, which defines and uses
brw_fence_insert(), an unlocked variant.

Reviewed-by: Rafael Antognolli <rafael.antognolli@intel.com>
Tested-by: Rafael Antognolli <rafael.antognolli@intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>