drm/hibmc: Call drm_irq_uninstall() unconditionally

Remove the check around drm_irq_uninstall(). The same test is
done by the function internally. The tested state in irq_enabled
is considered obsolete and should not be used by KMS drivers.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Tian Tao <tiantao6@hisilicon.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210625082222.3845-3-tzimmermann@suse.de