ocfs2: Make the ocfs2_caching_info structure self-contained.

We want to use the ocfs2_caching_info structure in places that are not
inodes.  To do that, it can no longer rely on referencing the inode
directly.

This patch moves the flags to ocfs2_caching_info->ci_flags, stores
pointers to the parent's locks on the ocfs2_caching_info, and renames
the constants and flags to reflect its independant state.

Signed-off-by: Joel Becker <joel.becker@oracle.com>