ovpnmain.cgi: Fixes bug13869 - shows values from vpnsettings in advanced server page

ovpnmain.cgi: Fixes bug13869 - shows values from vpnsettings in advanced server page

- In the previous version the cgiparams hash was filled from the ovpn/settings file.
   However with the new version of this file that is no longer done. For the values
   of protocol, redirect_gw, mssfix, dataciphers, route_push the hash file was changed
   from %cgiparams to %vpnsettings. This was not done for the values of dciphers, dauth
   or tlsauth. These values still got their entries from the %cgiparams hash but this
   hash is empty as it has not been filled.
- This patch replaces the use of $cgiparams with $vpnsettings.
- Tested this out on my vm testbed and confirmed that the saved values are now shown on
   the advanced settings wui page.

Fixes: bug13869
Tested-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>