gpu: host1x: Refactor channel allocation code

This is largely a rewrite of the Host1x channel allocation code, bringing
several changes:

- The previous code could deadlock due to an interaction
  between the 'reflock' mutex and CDMA timeout handling.
  This gets rid of the mutex.
- Support for more than 32 channels, required for Tegra186
- General refactoring, including better encapsulation
  of channel ownership handling into channel.c

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/gr3d.c

@@ -48,7 +48,7 @@ static int gr3d_init(struct host1x_client *client)
 
 	client->syncpts[0] = host1x_syncpt_request(client->dev, flags);
 	if (!client->syncpts[0]) {
-		host1x_channel_free(gr3d->channel);
+		host1x_channel_put(gr3d->channel);
 		return -ENOMEM;
 	}
 
@@ -67,7 +67,7 @@ static int gr3d_exit(struct host1x_client *client)
 		return err;
 
 	host1x_syncpt_free(client->syncpts[0]);
-	host1x_channel_free(gr3d->channel);
+	host1x_channel_put(gr3d->channel);
 
 	return 0;
 }