Add flag whether MTE state was forced

This will be used by mtectrl to remember whether the MTE state was
overriden using the force_on / force_off flags or set by the user. We
need that information when the force_on / force_off flag is reset.

Bug: 291106070
Change-Id: I6178f0b88b718e96e5c8ee39113848f422e5fb6d