perl: add testdepends for ssh

perl: add testdepends for ssh

fixes:

 DEBUG: [Running]$ ssh -l root -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -o LogLevel=ERROR 192.168.7.4 export PATH=/usr/sbin:/sbin:/usr/bin:/bin; perl -e '$_="Uryyb, jbeyq"; tr/a-zA-Z/n-za-mN-ZA-M/;print'
| DEBUG: time: 1548816904.4024463, endtime: 1548817204.397057
| DEBUG: Partial data from SSH call: ssh: connect to host 192.168.7.4 port 22: Connection refused

for master/thud/sumo

(From OE-Core rev: a590e7805e3bec5dd995f7ea0b9e79a21f82b48b)

Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>