Emulator: Fix loading 16-bit immediate value

The 8 lower bits are read first. The 8 higher bits come afterwards!

src/cpu.h

@@ -55,7 +55,7 @@ private:
 	uint8_t peekMemory(int32_t offset = 0) const;
 	uint8_t consumeMemory();
 
-	uint32_t immediate16() { return (consumeMemory() << 8) | consumeMemory(); }
+	uint32_t immediate16() { return consumeMemory() | (consumeMemory() << 8); }
 
 	void setBc(uint32_t value);
 	void setDe(uint32_t value);