GFS2: More automated code analysis fixes

A potentially uninitialised variable, some unreachable code,
and the main part of this, fixing the error path in the
unlink function.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --cc fs/gfs2/bmap.c
Simple merge

diff --cc fs/gfs2/file.c
Simple merge

diff --cc fs/gfs2/inode.c
Simple merge