[Bug]: armbian-bsp misses dependency on bc package

### What happened?

as discussed in #8143 the armbian-bsp packages miss a dependency on bc

### How to reproduce?

sudo apt purge bc
source /etc/update-motd.d/30-armbian-sysinfo
dpkg -S /etc/update-motd.d/30-armbian-sysinfo

### Branch

main (main development branch)

### On which host OS are you running the build script and observing this problem?

Ubuntu 24.04 Noble

### Are you building on Windows WSL2?

- [ ] Yes, my Ubuntu/Debian/OtherOS is running on WSL2

### Relevant log URL

_No response_

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct