[v2] ubi: fastmap: fix ubi->fm memory leak

[Markus Elfring]

> > You may occasionally put more than 60 characters into text lines
> > of such a change description.
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.18-rc4#n658

> Feel free to ignore everything Markus says.

Does your feedback indicate then also that Linux development process documentation may be overlooked any more?

Regards,
Markus