nk3: increase default finalization timeout to 30secs

[daringer]

This PR increases the default timeout for the finalization step after the update by the factor of 2 to 30secs.

Checklist

• [x] tested with Python3.9
• [x] run make check or make fix for the formatting check
• [x] signed commits

Test Environment and Execution

• OS: Arch
• device's model: nk3am
• device's firmware version: 1.3 alpha 20230320