PCI: Make pci_dev_is_disconnected() helper public for other drivers

PCI: Make pci_dev_is_disconnected() helper public for other drivers

Make pci_dev_is_disconnected() public so that it can be called from
Intel VT-d driver to quickly fix/workaround the surprise removal
unplug hang issue for those ATS capable devices on PCIe switch downstream
hotplug capable ports.

Beside pci_device_is_present() function, this one has no config space
space access, so is light enough to optimize the normal pure surprise
removal and safe removal flow.

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Tested-by: Haorong Ye <yehaorong@bytedance.com>
Signed-off-by: Ethan Zhao <haifeng.zhao@linux.intel.com>
Link: https://lore.kernel.org/r/20240301080727.3529832-2-haifeng.zhao@linux.intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>