selftests: rename jump label to static_keys

Commit 2bf9e0ab ("locking/static_keys: Provide a selftest")
renamed jump_label directory to static_keys and failed to update
the Makefile, causing the selftests build to fail.

This commit fixes it by updating the Makefile with the new name
and also moves the entry into the correct position to keep the
list alphabetically sorted.

Fixes: 2bf9e0ab

 ("locking/static_keys: Provide a selftest")
Signed-off-by: Bamvor Jian Zhang <bamvor.zhangjian@linaro.org>
Acked-by: Shuah Khan <shuahkh@osg.samsung.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>