CVE-2026-72240: mfd: sm501: Fix reference leak on failed device registration

In the Linux kernel, the following vulnerability has been resolved:

mfd: sm501: Fix reference leak on failed device registration

When platformdeviceregister() fails in sm501registerdevice(), the embedded struct device in pdev has already been initialized by deviceinitialize(), but the failure path only reports the error and returns without dropping the device reference for the current platform device:

sm501registerdevice() -> platformdeviceregister(pdev) -> deviceinitialize(&pdev->dev) -> setuppdevdmamasks(pdev) -> platformdeviceadd(pdev)

This leads to a reference leak when platformdeviceregister() fails. Fix this by calling platformdeviceput() before returning the error.

The issue was identified by a static analysis tool I developed and confirmed by manual review.