fix: restore correct COUNT values for DHT timing threshold

[baorepo]

Summary

• Restore COUNT timing threshold values that were incorrectly reduced in commit 69cabab
• The bad commit lowered all COUNT values across all CPU frequencies, breaking DHT11/DHT22 sensor reads

Problem

COUNT is the pulse-width threshold used to distinguish '0' bits (~26µs) from '1' bits (~70µs) in the DHT single-wire protocol. The read loop counts delayMicroseconds(1) iterations while the pin stays in a given state, then compares counter > _count.

On 16 MHz AVR, each loop iteration takes ~4-5µs (due to digitalRead overhead), so:

• '0' bit → counter ≈ 5-6
• '1' bit → counter ≈ 14-17

With COUNT=2 (the broken value), even a '0' bit exceeds the threshold, causing all bits to be read as '1' → garbage data.

Fix

Restore the battle-tested COUNT values from before 69cabab. Also fix the new frequency entries (10 MHz, 20 MHz, 40 MHz) that were added with incorrect values.

Freq	Broken COUNT	Restored COUNT
8 MHz	1	3
10 MHz	1	3
16 MHz	2	6
20 MHz	2	6
40 MHz	4	10
48 MHz	5	18
64 MHz	6	20
80 MHz	8	22
160 MHz	16	32
168 MHz	16	40

Fixes #27.

Test plan

• Verify DHT11 readings on Arduino Uno R3 (16 MHz AVR)
• Verify DHT22 readings on Arduino Uno R3
• Verify readings on 8 MHz AVR (e.g. Arduino Pro Mini 3.3V)
• Verify readings on SAMD21 (48 MHz) platforms like Seeeduino Xiao