drm/komeda: Initialize and enable output polling on Komeda

Initialize and enable output polling on Komeda.

Changes since v1:
1. Enable the polling before registering the driver;
2. Disable the polling after unregistering the driver.

Changes since v2:
1. If driver register failed, disable the polling.

Signed-off-by: Lowry Li (Arm Technology China) <lowry.li@arm.com>
Reviewed-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
Signed-off-by: james qian wang (Arm Technology China) <james.qian.wang@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1564733249-24329-1-git-send-email-lowry.li@arm.com