CVE-2025-38125

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

net: stmmac: make sure that ptp_rate is not 0 before configuring EST

If the ptp_rate recorded earlier in the driver happens to be 0, this
bogus value will propagate up to EST configuration, where it will
trigger a division by 0.

Prevent this division by 0 by adding the corresponding check and error
code.