Use functional abstraction for hooks

src/drivers/Spi.h

@@ -1,6 +1,7 @@
 #pragma once
 #include <cstdint>
 #include <cstddef>
+#include <functional>
 #include "drivers/SpiMaster.h"
 
 namespace Pinetime {
@@ -14,7 +15,7 @@ namespace Pinetime {
       Spi& operator=(Spi&&) = delete;
 
       bool Init();
-      bool Write(const uint8_t* data, size_t size, void (*TransactionHook)(bool));
+      bool Write(const uint8_t* data, size_t size, std::function<void(bool)> TransactionHook);
       bool Read(uint8_t* cmd, size_t cmdSize, uint8_t* data, size_t dataSize);
       bool WriteCmdAndBuffer(const uint8_t* cmd, size_t cmdSize, const uint8_t* data, size_t dataSize);
       void Sleep();