drm/komeda: Add irq handling

1. Added irq_handler/irq_enable/irq_disable to komeda_dev_func, then the
   Komeda-CORE can control the HW irq via these chip function.
2. Install irq and register irq_handler to system by DRM, so once the IRQ
   coming, the handling sequence is:

   komeda_kms_irq_handler(int irq, void *data)
        /* step 1. call into the CHIP to recognize event */
	mdev->funcs->irq_handler(mdev, &evts);

	/* step 2. notify the crtc to handle the events */
	for (i = 0; i < kms->n_crtcs; i++)
		komeda_crtc_handle_event(&kms->crtcs[i], &evts);

v2:
- Move get IRQ number into this change.
- Enable irq before drm_dev_register.

Signed-off-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>