selftests: livepatch: add missing fragments to config

When generating config with 'make defconfig kselftest-merge' fragment
CONFIG_TEST_LIVEPATCH=m isn't set.

Rework to enable CONFIG_LIVEPATCH and CONFIG_DYNAMIC_DEBUG as well.

Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>