x86/PCI: Add PIRQ routing table range checks

Verify that the PCI IRQ Routing Table header as well as individual slot 
entries are all wholly contained within the BIOS memory area.  Do not 
even call the checksum calculator if the header would overrun the area 
and then bail out early if any slot would.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2203301735510.22465@angie.orcam.me.uk