Limit the bit pulse counter to 2 * hw.freq
Limit the bit pulse counter to 2 * hw.freq

This is always enough, since realfreq <= hw.freq and a new pulse is
expected every one or two seconds.

The old value was round(2.5 * 1.5 * hw.freq), where 2.5 was 2.5 seconds
and 1.5 was for realfreq <= 1.5 * hw.freq.

rene0/dcf77pi,rene0/dcf77pi