ktap: add libelf PACKAGECONFIG also to ktap-module

* building ktap-module without elfutils fails with:
  ktap-module/0.4-r0/git/Makefile:107: No libelf found, disables symbol resolving, please install elfutils-libelf-devel/libelf-dev

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