./85/LED-strip_PWM_IR: Added a #define to DIS/EN IR_scan() on power-up.

Why?

I forgot about this 'feature' and spent a whole day chasing a
nox-existent hardware bug. I even re-spun the circuit board, added a
free wheeling diode for protection agains inductive kick-back... all for
nothing. DOH!

Luckily the board is very small and OSHPARK has free international
shipping now ;-)