Check for NULL alloc in cih_hash_entry

cache_inode_new_entry will check the return code in the next patch.

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
Fixup cache_inode_new_entry error paths and cleanup

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>