cmake: additional board revision comments addressed for #29990

This commit contains some additional review comments that was posted
after board revision PR #29990 was merged.

The follow-up changes are:
- Fixed typo: REVIVISION --> REVISION
- Renaming leftover in print message:
  zephyr_check_board_revision --> board_check_revision
- Fixed regex, to allow revision 10, 20, 30, 40, etc.
- digits --> number in comment

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
2 files changed