Fix NUM_ANALOG_INPUTS for Amperka WiFi slot

[evgenykochetkov]

It actually has 8 analog inputs:

Arduino/variants/wifi_slot/pins_arduino.h

Lines 49 to 57 in 9fb4a05

	// A0 will be assigned in "../generic/common.h"
	// static const uint8_t A0 = PIN_A0;
	static const uint8_t A1 = PIN_A1;
	static const uint8_t A2 = PIN_A2;
	static const uint8_t A3 = PIN_A3;
	static const uint8_t A4 = PIN_A4;
	static const uint8_t A5 = PIN_A5;
	static const uint8_t A6 = PIN_A6;
	static const uint8_t A7 = PIN_A7;