x86/pci/intel_mid_pci: Fix PCIBIOS_* return code handling

intel_mid_pci_irq_enable() uses pci_read_config_byte() that returns
PCIBIOS_* codes. The error handling, however, assumes the codes are
normal errnos because it checks for < 0.

intel_mid_pci_irq_enable() also returns the PCIBIOS_* code back to the
caller but the function is used as the (*pcibios_enable_irq) function
which should return normal errnos.

Convert the error check to plain non-zero check which works for
PCIBIOS_* return codes and convert the PCIBIOS_* return code using
pcibios_err_to_errno() into normal errno before returning it.

Fixes: 5b395e2b ("x86/platform/intel-mid: Make IRQ allocation a bit more flexible")
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240527125538.13620-2-ilpo.jarvinen@linux.intel.com