(#9796) ssh_authorized_key supports whitespace again

Remove the value validation for the name parameter.

1c7f0c3530 caused a regression: puppet does not support whitespace in
the name anymore, e.g. if you specify

ssh_authorized_key { 'fancy user':
  ensure => present,
  type   => rsa,
  key    => 'AAAAB3...iopMxe5aWw==',
}

you will get the error "Resourcename must not contain whitespace."

While spaces are in general used as a delimiter OpenSSH does support
these in the comment field and the provider did already handle
whitespace correctly. So the type should not forbid it.