drm/exynos: remove DRIVER_HAVE_IRQ feature

Exynos drm driver cannot support DRIVER_HAVE_IRQ feature because it uses
driver specific one instead of routine of drm framework to
install/uninstall irq handler.

Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>