x86/of: Return consistent error type from x86_of_pci_irq_enable()

x86_of_pci_irq_enable() returns PCIBIOS_* code received from
pci_read_config_byte() directly and also -EINVAL which are not
compatible error types. x86_of_pci_irq_enable() is used as
(*pcibios_enable_irq) function which should not return PCIBIOS_* codes.

Convert the PCIBIOS_* return code from pci_read_config_byte() into
normal errno using pcibios_err_to_errno().

Fixes: 96e0a079 ("x86: dtb: Add support for PCI devices backed by dtb nodes")
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240527125538.13620-1-ilpo.jarvinen@linux.intel.com