gnu: guile-ssh: Rename "guile2.2-ssh" to "guile-ssh".

* gnu/packages/ssh.scm (guile-ssh)[inputs]: Change GUILE-2.0 to
GUILE-2.2.
(guile2.2-ssh): Define using 'deprecated-package'.
(guile2.0-ssh): New variable.
* gnu/packages/package-management.scm (guix)[propagated-inputs]: Adjust
accordingly.