drm/amdgpu: move poll enabled/disable into non DC path

Some amd asics having reliable hotplug support don't call
drm_kms_helper_poll_init in driver init sequence. However,
due to the unified suspend/resume path for all asics, because
the output_poll_work->func is not set for these asics, a warning
arrives when suspending.

[ 90.656049] <TASK>
[ 90.656050] ? console_unlock+0x4d/0x100
[ 90.656053] ? __irq_work_queue_local+0x27/0x60
[ 90.656056] ? irq_work_queue+0x2b/0x50
[ 90.656057] ? __wake_up_klogd+0x40/0x60
[ 90.656059] __cancel_work_timer+0xed/0x180
[ 90.656061] drm_kms_helper_poll_disable.cold+0x1f/0x2c [drm_kms_helper]
[ 90.656072] amdgpu_device_suspend+0x81/0x170 [amdgpu]
[ 90.656180] amdgpu_pmops_runtime_suspend+0xb5/0x1b0 [amdgpu]
[ 90.656269] pci_pm_runtime_suspend+0x61/0x1b0

drm_kms_helper_poll_enable/disable is valid when poll_init is called in
amdgpu code, which is only used in non DC path. So move such codes into
non-DC path code to get rid of such warnings.

v1: introduce use_kms_poll flag in amdgpu as the poll stuff check
v2: use dc_enabled as the flag to simply code
v3: move code into non DC path instead of relying on any flag

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/2411
Fixes: a4e771729a51 ("drm/probe_helper: sort out poll_running vs poll_enabled")
Reported-by: Bert Karwatzki <spasswolf@web.de>
Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Suggested-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>