drm/amd/display: Fix deadlock during gpu reset v3

drm/amd/display: Fix deadlock during gpu reset v3

[Why]
during idle optimizations we acquire the dc_lock, this lock is also
acquired during gpu_reset so we end up hanging the system due to a
deadlock

[How]
If we are in gpu reset:
 - disable idle optimizations and skip calls to the dc function

v2: skip idle optimizations calls
v3: add guard for DCN

Fixes: 71338cb4a7c2b51 ("drm/amd/display: enable idle optimizations for linux (MALL stutter)")
Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>