options: Avoid needless assignment as reported by csbuild

The error was

 src/options.c:971:13: warning: Value stored to 'u' is never read
 #            u = 0;
 #            ^   ~
 src/options.c:971:13: note: Value stored to 'u' is never read
 #            u = 0;
 #            ^   ~
 #  969|           case SSH_OPTIONS_KBDINT_AUTH:
 #  970|           case SSH_OPTIONS_GSSAPI_AUTH:
 #  971|->             u = 0;
 #  972|               if (value == NULL) {
 #  973|                   ssh_set_error_invalid(session);

Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

src/options.c

@@ -968,7 +968,6 @@ int ssh_options_set(ssh_session session, enum ssh_options_e type,
         case SSH_OPTIONS_PUBKEY_AUTH:
         case SSH_OPTIONS_KBDINT_AUTH:
         case SSH_OPTIONS_GSSAPI_AUTH:
-            u = 0;
             if (value == NULL) {
                 ssh_set_error_invalid(session);
                 return -1;