include/hw/ide: Unexport pci_piix3_xen_ide_unplug()

include/hw/ide: Unexport pci_piix3_xen_ide_unplug()

This function was declared in a generic and public header, implemented
in a device-specific source file but only used in xen_platform. Given its
'aux' parameter, this function is more xen-specific than piix-specific.
Also, the hardcoded magic constants seem to be generic and related to
PCIIDEState and IDEBus rather than piix.

Therefore, move this function to xen_platform, unexport it, and drop the
"piix3" in the function name as well.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20220513180957.90514-4-shentey@gmail.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>