GFS2: Clean up symlink creation

This moves the symlink specific parts of inode creation
into the function where we initialise the rest of the
dinode. As a result we have one less place where we need
to look up the inode's buffer.

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

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

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