drm/amd/display: Add DPP & HUBP reset if power gate enabled on DCN314

[WHY]
On DCN314, using full screen application with enabled scaling like 150%,
175%, with overlay cursor, causes a second cursor to appear when changing
planes. Dpp cache is used to track the HW cursor enable. Since power gate
is disabled for hubp & dpp in DCN314, dpp_reset() zero'ed the dpp struct,
while the dpp hardware was not power gated.

So, when plane is changed in a full screen app, and the overlay cursor is
enabled, the cache is cleared, so the cache does not represent the actual
cursor state.

[HOW]
Added conditionals for dpp & hubp reset and their pg_control functions
only if according power_gate flags are enabled.

Reviewed-by: Sun peng Li <sunpeng.li@amd.com>
Signed-off-by: Ivan Lipski <ivlipski@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>