afsio: Don't leak memory on GetVenusFidBy* failure

afsio: Don't leak memory on GetVenusFidBy* failure

The GetVenusFid functions all allocate the fid structure immediately
upon entry to the function. When we return with an error, that structure
is never freed.

Update the call sites so that we don't leak this memory.

Caught by clang-analyzer

Change-Id: Iec62316d0fd542e70634f384c8319f90ba6b2649
Reviewed-on: http://gerrit.openafs.org/9187
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>