Simplify Tor logging restriction

Can use the "Log min-max <location>" syntax instead of declaring a
separate value for each logging level.

misc/tor/torrc

@@ -6,6 +6,4 @@ CookieAuthFileGroupReadable 1
 ExtORPortCookieAuthFileGroupReadable 1
 CacheDirectoryGroupReadable 1
 CookieAuthFile /var/lib/tor/control_auth_cookie
-Log debug file /dev/null
-Log info file /dev/null
-Log notice file /dev/null
+Log debug-notice file /dev/null