drm/amd/amdgpu: Correct gfx10's CG sequence

Incorrect CG sequence will cause gfx timedout,
if we keep switching power profile mode
(enter profile mod such as PEAK will disable CG,
exit profile mode EXIT will enable CG)
when run Vulkan test case(case used for test: vkexample).

Signed-off-by: Chengming Gui <Jack.Gui@amd.com>
Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Acked-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>