Kconfig: Refine test Kconfig configs

This patch has these refinements:

 - Add some important internal variables to build test. This
   is to align with lib/ext/tf-m-tests/reg_parse.cmake.
 - Add more test configs from test default configs.

Signed-off-by: Jianliang Shen <jianliang.shen@arm.com>
Change-Id: Ib38f5da30cf93d0589c62344a01614de381cbc3a
2 files changed