ANDROID: cpuidle: teo: Export a function that allows modifying util_threshold

There are some corner cases where we do worse in power because the
threshold is too low. Until these cases are better understood and
addressed upstream, provide a function for vendors to override this
value with something more suitable in their modules.

Bug: 289293494
Signed-off-by: Qais Yousef <qyousef@google.com>
Change-Id: I95dd36718a317f3fcb2a9f4bc87dd3390a4f7d7d