I hit the same problem while installing HDP 2.6.4 on POWER systems. I got over the problem be adding the optional package to the repos. If you have a network or local RHEL repository you need to have the following listed as one of the baseurls:
baseurl=ftp://<userID>:<password>@<ftpHostName>/redhat/release_cds/<rhelRelease>/Server-optional/ppc64le/os/
e.g.:
baseurl=ftp://<userID>:<password>@<ftpHostName>/redhat/release_cds/RHEL-7.4-GA/Server-optional/ppc64le/os/