PCI/VGA: Replace vga_is_firmware_default() with a screen info check

PCI/VGA: Replace vga_is_firmware_default() with a screen info check

vga_is_firmware_default() checks firmware resources to find the owner
framebuffer resources to find the firmware PCI device.  This is an
open coded implementation of screen_info_pci_dev().  Switch to using
screen_info_pci_dev() instead.

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://lore.kernel.org/r/20250811162606.587759-3-superm1@kernel.org
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>