platform/x86/intel/speed_select_if: Convert PCIBIOS_* return codes to errnos

isst_if_probe() uses pci_read_config_dword() that returns PCIBIOS_*
codes. The return code is returned from the probe function as is but
probe functions should return normal errnos. A proper implementation
can be found in drivers/leds/leds-ss4200.c.

Convert PCIBIOS_* return codes using pcibios_err_to_errno() into
normal errno before returning.

Fixes: d3a2358 ("platform/x86: ISST: Add Intel Speed Select mmio interface")
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://patch.msgid.link/20251117033354.132-1-vulab@iscas.ac.cn
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Author: ISCAS-Vulab

drivers/platform/x86/intel/speed_select_if/isst_if_mmio.c

@@ -108,11 +108,11 @@ static int isst_if_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	ret = pci_read_config_dword(pdev, 0xD0, &mmio_base);
 	if (ret)
-		return ret;
+		return pcibios_err_to_errno(ret);
 
 	ret = pci_read_config_dword(pdev, 0xFC, &pcu_base);
 	if (ret)
-		return ret;
+		return pcibios_err_to_errno(ret);
 
 	pcu_base &= GENMASK(10, 0);
 	base_addr = (u64)mmio_base << 23 | (u64) pcu_base << 12;