Slight polish to DMA (#1856)

* Slight polish to DMA

- Default-initialize members explicitly
- Mark some methods as const noexcept
- Initialize DMA::MRAMBurstTable to DMATiming::MRAMDummy
- Use the default destructor

* Move DMA_Timings definitions to a source file

- To ensure constant and unique addresses

* Include some extra DMA members in the savestate

* Simplify serializing the DMA table

- Extend the dummy table to 256 bytes (same length as the real ones)

* Revert the type change to DMA::DoSavestate

* Keep the MRAMBurstTable inside the DMA class, instead of using a pointer

- If we use a pointer to an external table, then we can't use it in savestates (else that external table gets overwritten)

src/Savestate.h

@@ -25,7 +25,7 @@
 #include "types.h"
 
 #define SAVESTATE_MAJOR 10
-#define SAVESTATE_MINOR 0
+#define SAVESTATE_MINOR 1
 
 class Savestate
 {