gpu: nvgpu: add common fuse APIs

Add a new file common/linux/fuse.c for common fuse
operations with below APIs
nvgpu_tegra_fuse_read()
nvgpu_tegra_fuse_write()
nvgpu_tegra_get_gpu_speedo_id()

Export the APIs in header <nvgpu/fuse.h>

Jira NVGPU-49
Jira NVGPU-75

Change-Id: I5b0b0772584a5d408b23e629df9c5f73ecc05f6b
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/1483860
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

drivers/gpu/nvgpu/common/linux/fuse.c

@@ -0,0 +1,31 @@
+/*
+ * 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.
+ */
+
+#include <soc/tegra/fuse.h>
+
+#include <nvgpu/fuse.h>
+
+int nvgpu_tegra_fuse_read(unsigned long offset, u32 *value)
+{
+	return tegra_fuse_readl(offset, value);
+}
+
+void nvgpu_tegra_fuse_write(u32 value, unsigned long offset)
+{
+	tegra_fuse_control_write(value, offset);
+}
+
+int nvgpu_tegra_get_gpu_speedo_id(void)
+{
+	return tegra_sku_info.gpu_speedo_id;
+}