CVE-2026-72233: batman-adv: bla: reacquire gw address after skb realloc

In the Linux kernel, the following vulnerability has been resolved:

batman-adv: bla: reacquire gw address after skb realloc

The pskbmaypull() called by batadvblaisbackbonegw() could reallocate the buffer behind the skb. Variables which were pointing to the old buffer need to be reassigned to avoid an use-after-free.