zebra: Do not retry in 30 seconds on pw reachability failure

Currently the zebra pw code has setup a retry to install the
pw after 30 seconds when it is decided that reachability to
the pw is gone.  This causes a failure mode where the
pw code just goes and re-installs the pw after 30 seconds
in the non-reachability case.  Instead it should just be
reinstalling after reachability is restored.

Signed-off-by: Donald Sharp <sharpd@nvidia.com>

zebra/zebra_pw.c

@@ -147,7 +147,6 @@ void zebra_pw_update(struct zebra_pw *pw)
 {
  if (zebra_pw_check_reachability(pw) < 0) {
  zebra_pw_uninstall(pw);
- zebra_pw_install_failure(pw, PW_NOT_FORWARDING);
  /* wait for NHT and try again later */
  } else {
  /*
@@ -167,6 +166,14 @@ static void zebra_pw_install(struct zebra_pw *pw)
 
  hook_call(pw_install, pw);
  if (dplane_pw_install(pw) == ZEBRA_DPLANE_REQUEST_FAILURE) {
+ /*
+ * Realistically this is never going to fail passing
+ * the pw data down to the dplane. The failure modes
+ * look like impossible events but we still return
+ * on them.... but I don't see a real clean way to remove this
+ * at all. So let's just leave the retry mechanism for
+ * the moment.
+ */
  zebra_pw_install_failure(pw, PW_NOT_FORWARDING);
  return;
  }