Use size_t in some DSP code code

Source/Core/Common/Hash.h

@@ -12,7 +12,7 @@ namespace Common
 {
 u32 HashFletcher(const u8* data_u8, size_t length);  // FAST. Length & 1 == 0.
 u32 HashAdler32(const u8* data, size_t len);         // Fairly accurate, slightly slower
-u32 HashEctor(const u8* ptr, int length);            // JUNK. DO NOT USE FOR NEW THINGS
+u32 HashEctor(const u8* ptr, size_t length);         // JUNK. DO NOT USE FOR NEW THINGS
 u64 GetHash64(const u8* src, u32 len, u32 samples);
 void SetHash64Function();
 }  // namespace Common