ATMEGA 168P add interrupt pins mapping to interrupt_pins.h

[t0nd4]

Please add support for ATMEGA 168P interrupt pins, mapping is the same as ATMEGA 168.
Here is the solution:

#elif defined(__AVR_ATmega328P__) || defined(__AVR_ATmega328PB__) ||defined(__AVR_ATmega168__) || defined(__AVR_ATmega8__)||defined(__AVR_ATmega168P__)