Fix preq frame process and peer link frame baselen.

[Javier Cardona]

> Yes, I agree with you, and this patch is just to check whether this PREQ is valid with
> the ttl it contains instead of local TTL, and the local TTL has also been provided for
> PREP further process.

I'm still unconvinced with that change.  The ttl check you refer to is done on
transmission: PREQs with ttl of zero are never transmitted.  See further down in
that same function:

	ttl = PREQ_IE_TTL(preq_elem);
	lifetime = PREQ_IE_LIFETIME(preq_elem);
	if (ttl <= 1) {
		/* supress frame */

Furthermore, with the change you propose, you open the possibility for PREPs to
be transmitted with ttl=0 (if ifmsh->mshcfg.dot11MeshTTL was set to zero).

Regarding your baselen explanation, I now understand it and agree to the
suggested change.  Your initial patch submission was reversed and I got confused
looking at two version of the same.

I've created a new series with the parts of your patch that I agree with.  They
follow this e-mail.

Thanks!

Javier