Incorrect CRC calculation in Riello driver.

[cool0nik]

In file nut/drivers/riello.c

This line:
pom = (pom << 8) ^ (pom << 3) ^ (pom >> 4);
was replaced by:
pom = (uint16_t)(pom << 8);
pom ^= (pom << 3);
pom ^= (pom >> 4);

This is wrong changes.
The result of CRC calculation was changed.
UPS does not working with this change and change should be reverted.

This "optimization" was introduced here:
6a2e042

Issue was found during upgrade Debein 11 -> 12.
from
Network UPS Tools - Riello serial driver 0.03 (2.7.4)
to
Network UPS Tools - Riello serial driver 0.07 (2.8.0)

[jimklimov]

Thanks for the report. I also see now what went wrong with that change, sorry about that.

Would you be able to check the PR above, with e.g. https://github.com/networkupstools/nut/wiki/Building-NUT-for-in%E2%80%90place-upgrades-or-non%E2%80%90disruptive-tests ?