drm/amdgpu/gfx10: fix resume failure when enabling async gfx ring

'adev->in_suspend' code path is missing in gfx_v10_0_gfx_init_queue()

Signed-off-by: Xiaojie Yuan <xiaojie.yuan@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>