firmware/sysfb: Create firmware device only for enabled PCI devices

Test if the firmware framebuffer's parent PCI device, if any, has
been enabled. If not, the firmware framebuffer is most likely not
working. Hence, do not create a device for the firmware framebuffer
on disabled PCI devices.

So far, efifb tracked the status of the PCI parent device internally
and did not bind if it was disabled. This patch implements the
functionality for all PCI-based firmware framebuffers.

v3:
	* make commit message more precise (Sui)
v2:
	* rework sysfb_pci_dev_is_enabled() (Javier)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240212090736.11464-6-tzimmermann@suse.de