drm/amdgpu: fix error handling in amdgpu_cs_user_fence_chunk

drm/amdgpu: fix error handling in amdgpu_cs_user_fence_chunk

BugLink: https://bugs.launchpad.net/bugs/1836426
[ Upstream commit 0165de983272d1fae0809ed9db47c46a412279bc ]

Slowly leaking memory one page at a time :)

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>