In function pci1xxxx_spi_probe, there is a potential null pointer that
may be caused by a failed memory allocation by the function devm_kzalloc.
Hence, a null pointer check needs to be added to prevent null pointer
dereferencing later in the code.

To fix this issue, spi_bus->spi_int[iter] should be checked. The memory
allocated by devm_kzalloc will be automatically released, so just directly
return -ENOMEM without worrying about memory leaks.

References

• https://nvd.nist.gov/vuln/detail/CVE-2024-24862
• https://bugzilla.openanolis.cn/show_bug.cgi?id=8748