GFS2: Fix uninitialized VFS inode in gfs2_create_inode

When gfs2_create_inode() fails due to quota violation, the VFS
inode is not completely uninitialized. This can cause a list
corruption error.

This patch correctly uninitializes the VFS inode when a quota
violation occurs in the gfs2_create_inode codepath.

Resolves: rhbz#1059808
Signed-off-by: Abhi Das <adas@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>