drm: zynqmp_dp: Convert to a hard IRQ

Now that all of the sleeping work is done outside of the IRQ, we can
convert it to a hard IRQ. Shared IRQs may be triggered even after
calling disable_irq, so use free_irq instead which removes our callback
altogether.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240809193600.3360015-5-sean.anderson@linux.dev