ACPI: PCI: IRQ: Fix INTx GSIs signedness

ACPI: PCI: IRQ: Fix INTx GSIs signedness

In ACPI Global System Interrupts (GSIs) are described using a 32-bit
value.

ACPI/PCI legacy interrupts (INTx) parsing code treats GSIs as 'int',
which poses issues if the GSI interrupt value is a 32-bit value with the
MSB set (as required in some interrupt configurations - eg ARM64 GICv5
systems) because acpi_pci_link_allocate_irq() treats a negative gsi
return value as a failed GSI allocation (and acpi_irq_get_penalty()
would trigger an out-of-bounds array dereference if the 'irq' param is
a negative value).

Fix ACPI/PCI legacy INTx parsing by converting variables representing
GSIs from 'int' to 'u32' bringing the code in line with the ACPI
specification and fixing the current parsing issue.

Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20260105101705.36703-1-lpieralisi@kernel.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>