drm/amdgpu: Avoid extra evict-restore process.

commit 1f02f204 upstream.

If vm belongs to another process, this is fclose after fork,
wait may enable signaling KFD eviction fence and cause parent process queue evicted.

[677852.634569]  amdkfd_fence_enable_signaling+0x56/0x70 [amdgpu]
[677852.634814]  __dma_fence_enable_signaling+0x3e/0xe0
[677852.634820]  dma_fence_wait_timeout+0x3a/0x140
[677852.634825]  amddma_resv_wait_timeout+0x7f/0xf0 [amdkcl]
[677852.634831]  amdgpu_vm_wait_idle+0x2d/0x60 [amdgpu]
[677852.635026]  amdgpu_flush+0x34/0x50 [amdgpu]
[677852.635208]  filp_flush+0x38/0x90
[677852.635213]  filp_close+0x14/0x30
[677852.635216]  do_close_on_exec+0xdd/0x130
[677852.635221]  begin_new_exec+0x1da/0x490
[677852.635225]  load_elf_binary+0x307/0xea0
[677852.635231]  ? srso_alias_return_thunk+0x5/0xfbef5
[677852.635235]  ? ima_bprm_check+0xa2/0xd0
[677852.635240]  search_binary_handler+0xda/0x260
[677852.635245]  exec_binprm+0x58/0x1a0
[677852.635249]  bprm_execve.part.0+0x16f/0x210
[677852.635254]  bprm_execve+0x45/0x80
[677852.635257]  do_execveat_common.isra.0+0x190/0x200

Suggested-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Gang Ba <Gang.Ba@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>