drm/amdgpu/display: Remove unnecessary conversion to bool

Fix the following coccicheck warnings:

./drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c:956:52-57: WARNING:
conversion to bool not needed here.

./drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c:8311:16-21: WARNING:
conversion to bool not needed here.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -993,7 +993,7 @@ static void event_mall_stutter(struct work_struct *work)
 
 
 	dc_allow_idle_optimizations(
-		dm->dc, dm->active_vblank_irq_count == 0 ? true : false);
+		dm->dc, dm->active_vblank_irq_count == 0);
 
 	DRM_DEBUG_DRIVER("Allow idle optimizations (MALL): %d\n", dm->active_vblank_irq_count == 0);