drm/amdgpu: remove conversion to bool in amdgpu_device.c

The '>' expression itself is bool, no need to convert it to bool again.
This fixes the following coccicheck warning:

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c:3004:68-73: WARNING:
conversion to bool not needed here
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

@@ -2998,7 +2998,7 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	INIT_WORK(&adev->xgmi_reset_work, amdgpu_device_xgmi_reset_func);
 
 	adev->gfx.gfx_off_req_count = 1;
-	adev->pm.ac_power = power_supply_is_system_supplied() > 0 ? true : false;
+	adev->pm.ac_power = power_supply_is_system_supplied() > 0;
 
 	/* Registers mapping */
 	/* TODO: block userspace mapping of io register */