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>
afsio: Ignore return values from afscp_SetDefault*

We don't do anything with the return values from afscp_SetDefaultCell
or afscp_SetDefaultRealm, so just ignore them.

Caught by clang-analyzer

Change-Id: Ib7d9e637e5d08df28ad0085302811b243fb21768
Reviewed-on: http://gerrit.openafs.org/9188
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>