drm/i915: support struct device and pci_dev in to_intel_display()

drm/i915: support struct device and pci_dev in to_intel_display()

Now that both xe and i915 store struct drm_device in drvdata, we can
trivially support struct device and struct pci_dev in
to_intel_display().

We do need to check for NULL drvdata before converting it into struct
intel_device pointer, though. Do it in __drm_device_to_intel_display().

v2: Add NULL check in __drm_device_to_intel_display() (Gustavo)

Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com> # v1
Link: https://patchwork.freedesktop.org/patch/msgid/f025a3fa4422725c78baac4501ad3ecc9e5b40d5.1724942754.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>