pkd: omit -v for dbclient by default

The `-v` is only recognized by `dbclient` when dropbear is built
in its DEBUG_TRACE mode.  Omit that flag by default to avoid a
warning log emitted to stderr.

Signed-off-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

tests/pkd/pkd_client.h

@@ -82,7 +82,6 @@
     DROPBEAR_BINARY " "      \
     "-y -y "                 \
     "-i " CLIENT_ID_FILE " " \
-    "-v "                    \
     "1> %s.out "             \
     "2> %s.err "