If you want to install Original LTS Ubuntu 16.04 (with initial LTS Kernel 4.4) on Power9, you were / are out of luck. This is because full kernel support for Power9 got in from 4.10 on wards.
But to some jubilation, 16.04.3 LTS got released today (08/03/17) with support for 17.04 Kernel (4.10). So work around to install Ubuntu LTS on Power9 is to use 16.04.03 LTS HWE kernel / initrd instead of ones I indicated in my previous blog post:
Again, Follow the same procedure in previous blog post BUT with NEW kernel / initrd links.
Enjoy the first LTS port on Power9