usb: xhci: Avoid showing warnings for dying controller

usb: xhci: Avoid showing warnings for dying controller

When a USB4 dock is unplugged from a system it won't respond to ring
events. The PCI core handles the surprise removal event and notifies
all PCI drivers. The XHCI PCI driver sets a flag that the device is
being removed, and when the device stops responding a flag is also
added to indicate it's dying.

When that flag is set don't bother to show warnings about a missing
controller.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20250717073107.488599-3-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>