selftests: memory-hotplug: delete RUN_TESTS and EMIT_TESTS overrides

Delete RUN_TESTS and EMIT_TESTS overrides and use common defines in
lib.mk. Common defines work after making the change the test to run
with ratio=2 as the default mode to be able to invoke the test without
the "-r 2" argument from the common RUN_TESTS and EMIT_TESTS.

The run_full_tests target now calls the test with "-r 10".

Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Reviewed-by: Anders Roxell <anders.roxell@linaro.org>
Reviewed-by:  <Lei.Yang@windriver.com>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>