Method sleep

SerialFlashChip.cpp:397–404

chips tested: https://github.com/PaulStoffregen/SerialFlash/pull/12#issuecomment-169596992

// chips tested: https://github.com/PaulStoffregen/SerialFlash/pull/12#issuecomment-169596992
//
void SerialFlashChip::sleep()
{
	if (busy) wait();
	SPIPORT.beginTransaction(SPICONFIG);
	CSASSERT();
	SPIPORT.transfer(0xB9); // Deep power down command
	CSRELEASE();
}

void SerialFlashChip::wakeup()
{