graphics/drm-515-kmod: Update to drm_v5.15.25_3

• i915: Suggest installing gpu-firmware-kmod instaed of printing a link to the linux-firmware git repository if the firmware couldn't be loaded
• Add linuxkpi_version.mk: This will help nvidia-drm to track which linux version it needs to be compatible with.

Sponsored by: Beckhoff Automation GmbH & Co. KG