Merge pull request #6342 from benlye/benlye-fix-softspi

Fix softspi variant conditional for 1284p

Marlin/softspi.h

 || defined(__AVR_ATmega324__)\
 || defined(__AVR_ATmega16__)
 
-#ifdef defined(VARIANT_MIGHTY)
+#if defined(VARIANT_MIGHTY)
 // Mighty Layout
 static const pin_map_t pinMap[] = {
   {&DDRB, &PINB, &PORTB, 0},  // B0  0

Marlin/temperature.cpp

 #include "temperature.h"
 #include "thermistortables.h"
 #include "language.h"
-#include "spi.h"
+
+#if ENABLED(HEATER_0_USES_MAX6675)
+  #include "spi.h"
+#endif
+
 #if ENABLED(BABYSTEPPING)
   #include "stepper.h"
 #endif