drm/amd/amdgpu/amdgpu_debugfs: Fix a couple of misnamed functions

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c:1004: warning: expecting prototype for amdgpu_debugfs_regs_gfxoff_write(). Prototype was for amdgpu_debugfs_gfxoff_write() instead
 drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c:1053: warning: expecting prototype for amdgpu_debugfs_regs_gfxoff_status(). Prototype was for amdgpu_debugfs_gfxoff_read() instead

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c

@@ -990,7 +990,7 @@ static ssize_t amdgpu_debugfs_gpr_read(struct file *f, char __user *buf,
 }
 
 /**
- * amdgpu_debugfs_regs_gfxoff_write - Enable/disable GFXOFF
+ * amdgpu_debugfs_gfxoff_write - Enable/disable GFXOFF
  *
  * @f: open file handle
  * @buf: User buffer to write data from
@@ -1041,7 +1041,7 @@ static ssize_t amdgpu_debugfs_gfxoff_write(struct file *f, const char __user *bu
 
 
 /**
- * amdgpu_debugfs_regs_gfxoff_status - read gfxoff status
+ * amdgpu_debugfs_gfxoff_read - read gfxoff status
  *
  * @f: open file handle
  * @buf: User buffer to store read data in