Move SI_DMA_DELA define to SI.hpp; doesn't need to be visible outside

src/backend/core/mmio/SI.hpp

@@ -36,4 +36,5 @@ struct SI {
 };
 
 static void DMA(Mem& mem, Registers& regs);
+#define SI_DMA_DELAY (65536 * 2)
 }

src/common.hpp

@@ -35,6 +35,5 @@ using m128i = __m128i;
 #define ELEMENT_INDEX(i) (7 - (i))
 #define BYTE_INDEX(i)   (15 - (i))
 
-#define SI_DMA_DELAY (65536 * 2)
 #define unlikely(exp) __builtin_expect(exp, 0)
 #define likely(exp) __builtin_expect(exp, 1)