drm/amd/display: Disable idle reallow as part of command/gpint execution

[Why]
Workaroud for a race condition where DMCUB is in the process of
committing to IPS1 during the handshake causing us to miss the
transition into IPS2 and touch the INBOX1 RPTR causing a HW hang.

[How]
Disable the reallow to ensure that we have enough of a gap between entry
and exit and we're not seeing back-to-back wake_and_executes.

Reviewed-by: Ovidiu Bunea <ovidiu.bunea@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>