drm/tilcdc: use pm_runtime_irq_safe()

tilcdc calls runtime PM get/put functions everywhere. Some of those
places will be called in irq context, crashing the driver.

As a quick fix, use pm_runtime_irq_safe() for tilcdc.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Jyri Sarha <jsarha@ti.com>