[video_core] Simplify DMA options (#525)

This simplifies DMA options in a clearer and more objective way.

Co-authored-by: PavelBARABANOV <pavelbarabanov94@gmail.com>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/525
Reviewed-by: crueter <crueter@eden-emu.dev>
Reviewed-by: Shinmegumi <shinmegumi@eden-emu.dev>
Co-authored-by: MaranBr <maranbr@outlook.com>
Co-committed-by: MaranBr <maranbr@outlook.com>

src/common/settings.h

@@ -443,7 +443,7 @@ struct Values {
     SwitchableSetting<DmaAccuracy, true> dma_accuracy{linkage,
                                                       DmaAccuracy::Default,
                                                       DmaAccuracy::Default,
-                                                      DmaAccuracy::Extreme,
+                                                      DmaAccuracy::Safe,
                                                       "dma_accuracy",
                                                       Category::RendererAdvanced,
                                                       Specialization::Default,
@@ -783,6 +783,9 @@ void UpdateGPUAccuracy();
 bool IsGPULevelExtreme();
 bool IsGPULevelHigh();
 
+bool IsDMALevelDefault();
+bool IsDMALevelSafe();
+
 bool IsFastmemEnabled();
 void SetNceEnabled(bool is_64bit);
 bool IsNceEnabled();