drm/amdgpu: fix documentation for amdgpu_gem_prime_export

Drop extra function parameter.
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -321,7 +321,6 @@ const struct dma_buf_ops amdgpu_dmabuf_ops = {
 
 /**
  * amdgpu_gem_prime_export - &drm_driver.gem_prime_export implementation
- * @dev: DRM device
  * @gobj: GEM BO
  * @flags: Flags such as DRM_CLOEXEC and DRM_RDWR.
  *