video_core: Add MSAA registers in 3D engine and TIC

This adds the registers used for multisampling. It doesn't implement
anything for now.

src/video_core/textures/texture.h

@@ -131,6 +131,20 @@ enum class SwizzleSource : u32 {
     OneFloat = 7,
 };
 
+enum class MsaaMode : u32 {
+    Msaa1x1 = 0,
+    Msaa2x1 = 1,
+    Msaa2x2 = 2,
+    Msaa4x2 = 3,
+    Msaa4x2_D3D = 4,
+    Msaa2x1_D3D = 5,
+    Msaa4x4 = 6,
+    Msaa2x2_VC4 = 8,
+    Msaa2x2_VC12 = 9,
+    Msaa4x2_VC8 = 10,
+    Msaa4x2_VC24 = 11,
+};
+
 union TextureHandle {
     TextureHandle(u32 raw) : raw{raw} {}
 
@@ -197,6 +211,7 @@ struct TICEntry {
     union {
         BitField<0, 4, u32> res_min_mip_level;
         BitField<4, 4, u32> res_max_mip_level;
+        BitField<8, 4, MsaaMode> msaa_mode;
         BitField<12, 12, u32> min_lod_clamp;
     };