drm/omap: Remove hdmi5_core_handle_irqs()

hdmi5_core_handle_irqs() is a function that was copied from omapdss by
commit f76ee892 ("omapfb: copy omapdss & displays for omapfb")

but it wasn't used in the original anyway.

Remove it.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241218020124.278925-1-linux@treblig.org