Remove duplicate strdup() calls

Remove duplicate strdup() calls

The arguments of openconnect_set_mobile_info() have been strdup'ed:
- prior to passing them to openconnect_set_mobile_info(),
- inside openconnect_set_mobile_info().

We don't need both. I have chosen to keep the strdup() call inside
openconnect_set_mobile_info(), and discard the strdup() of the arguments
just before calling openconnect_set_mobile_info().

Signed-off-by: Dimitri Papadopoulos <3350651-DimitriPapadopoulos@users.noreply.gitlab.com>