serial: icom: Convert PCIBIOS_* return codes to errnos

serial: icom: Convert PCIBIOS_* return codes to errnos

icom_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 them.

Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
Link: https://patch.msgid.link/20251117040710.1544-1-vulab@iscas.ac.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>