interactive: Generalize timer->base flags handling fix
To prepare for addition of another flag, generalize timer->base flags
handling.

* Rename from TBASE_*_FLAG to TIMER_* and make them LU constants.

* Define and use TIMER_FLAG_MASK for flags masking so that multiple
  flags can be handled correctly.

Signed-off-by: GuneetAtwal <harjinder767@gmail.com>