drm/i915: Simplify expression &to_i915(dev)->drm

to_i915 is defined as

	container_of(dev, struct drm_i915_private, drm);

So for a struct drm_device *dev, to_i915(dev)->drm is just dev. Simplify
accordingly.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230721212133.271118-1-u.kleine-koenig@pengutronix.de