Print the desired partition index together with the starting sector and
the size in sectors. Otherwise, when only one code partition is
desired, the configuration partition (/cfg) may not end in the third
slice, thus breaking the scripts that expect it there.
This was the previous approach, changed in 587c054bea0f ("nanobsd: Use
gpart and create code image before full disk image"), where the
partition index was printed as the first column.
Fix it by printing the index as the last column to reduce the chances of
breaking current overrides, and using it as the gpart index.
PR: 262098
Fixes: 587c054bea0f ("nanobsd: Use gpart and create code image before full disk image")