[U-Boot] [PATCH 2/2] rockchip: Remove obsolete references to pyelftools

[Chris Webb]

Oops, sorry; I'm an idiot. The synopsys board does indeed still use
pyelftools, and therefore while these are correct:

>  board/rockchip/evb_rk3399/README | 6 ------
>  doc/README.rockchip              | 4 ----

these removals are incorrect:

>  .travis.yml                      | 1 -
>  board/synopsys/hsdk/README       | 7 -------

Please disregard this second tidy-up patch for now.