Add line for Atmega4808

[andonoc]

Hello,
sorry but i cant use GIT properly and i don't know how to make a pull request.
For using a ATMEGA4808 i changed line 18 in util/OneWire_direct_gpio.h to

#if defined(AVR_ATmega4809) || (AVR_ATmega4808)

after this change the library works for me.

[sameSEA]

Thank this, it saved me time!
With Platformio and MegaCoreX that line 18 should be:
#if defined(__AVR_ATmega4809__) || defined(__AVR_ATmega4808__)

or just
#if defined(MEGACOREX)