drm/amd/display: Create debug option to disable v.active clock change policy.

[WHY]
It has been a useful option in debugging GFXOFF and P.State Change issues.
May be required as for platform specific workaround.

[HOW]
Create option in enum dc_debug_options, "disable_vactive_clock_change".
When it is set, dm_dram_clock_change_vactive, will translate into
p_state_change_support: false.

Signed-off-by: David Galiffi <David.Galiffi@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>