drm/amdgpu/mes: Fix an error handling path in amdgpu_mes_self_test()

if amdgpu_mes_ctx_alloc_meta_data() fails, we should call amdgpu_vm_fini()
to handle amdgpu_vm_init().

Add a new lable before amdgpu_vm_init() and goto this lable when
amdgpu_mes_ctx_alloc_meta_data() fails.

Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>