gpu: host1x: Make host1x header file public

In preparation to support host1x clients other than DRM, move this
header into a public location.

Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/drivers/gpu/host1x/hw/channel_hw.c b/drivers/gpu/host1x/hw/channel_hw.c
index ee19962..c950bc6 100644
--- a/drivers/gpu/host1x/hw/channel_hw.c
+++ b/drivers/gpu/host1x/hw/channel_hw.c
@@ -16,10 +16,11 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <linux/host1x.h>
 #include <linux/slab.h>
+
 #include <trace/events/host1x.h>
 
-#include "host1x.h"
 #include "host1x_bo.h"
 #include "channel.h"
 #include "dev.h"