Do not truncate office phones in finger's summary listing

When finger is invoked as as "finger username", it produces the
long listing by default, and phones numbers are pretty-printed
by the prphone() function. When invoked as just "finger", the
same pretty-printing happens, but is truncated at 9 characters.
Given the summary listing is already greater than 80 columns,
making it even wider is of no harm.

Approved by: rpaulo (mentor)
Differential Revision: https://reviews.freebsd.org/D5638