aklog: Don't reference freed node whilst deleting

aklog: Don't reference freed node whilst deleting

Because deletion is implemented using a for loop, the step of the
loop that moves us to the next node references freed memory when
we've deleted an element. Fix this by just shortcircuiting the
return from the function so we immediately exit.

Change-Id: Ia820b20ce5937ac86d849cb746b3bc21f46550fa
Reviewed-on: http://gerrit.openafs.org/9161
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>