gpu: nvgpu: Make LTC disabling common code

Refactor the sync_debugfs LTC HAL op so that the logic to enable
or disable LTC goes to common code nvgpu_ltc_sync_enabled() and
the LTC HAL set_enabled only performs the hardware register access.

Create a new common function nvgpu_init_ltc_support() to initialize
the LTC software variable, and move hardware initialization of LTC to
be called from it.

JIRA NVGPU-62

Change-Id: Ib1cf4f5b83ca3dac08407464ed56a732e0a33923
Signed-off-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1528262
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/include/nvgpu/ltc.h

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2017, NVIDIA CORPORATION.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+#ifndef __NVGPU_LTC_H__
+#define __NVGPU_LTC_H__
+
+struct gk20a;
+
+int nvgpu_init_ltc_support(struct gk20a *g);
+void nvgpu_ltc_sync_enabled(struct gk20a *g);
+
+#endif