drm/amd/display: Add unknown clk state.

[Why]
System hang during S0i3 if DP only connected due to clk is disabled when
doing link training.
During S0i3, clk is disabled while the clk state is updated when ini_hw
called, and at the moment clk is still disabled which indicating a wrong
state for next time trying to enable clk.

[How]
Add an unknown state and initialize it during int_hw, make sure enable clk
command be sent to smu.

Signed-off-by: Yongqiang Sun <yongqiang.sun@amd.com>
Reviewed-by: Eric Yang <eric.yang2@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>