Revert "meta-samsung: tuna.conf include also tune-cortexa9"

* this can be only in webOS-ports/master, it's causing different
  checksums between grouper and tuna

This reverts commit 3132ee1ab5f7d5c6ecb866623bafd780dee5eeb1.

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>