video: Provide screen_info_get_pci_dev() to find screen_info's PCI device

Add screen_info_get_pci_dev() to find the PCI device of an instance
of screen_info. Does nothing on systems without PCI bus.

v3:
	* search PCI device with pci_get_base_class() (Sui)
v2:
	* remove ret from screen_info_pci_dev() (Javier)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240212090736.11464-3-tzimmermann@suse.de