Fix #25499 : Frets >= 10 in tabs with linked staves.

When entering frets >= 10 in tabs with linked staves, the notes in linked staves are wrong (debug builds do assert!).

Once adding the 2nd digit, the tpc's of the resulting note were not set.

Raised in forum post: http://musescore.org/fr/node/25499
Merge pull request #859 from mgavioli/fix_25499_TABS_entering_frets_greater_than_9

Fix #25499 : Frets >= 10 in tabs with linked staves.