GSP: Implement SetBufferSwap.

src/core/hle/service/gsp.h

@@ -64,6 +64,18 @@ struct InterruptRelayQueue {
 static_assert(sizeof(InterruptRelayQueue) == 0x40,
     "InterruptRelayQueue struct has incorrect size");
 
+struct FrameBufferInfo {
+    BitField<0, 1, u32> active_fb; // 0 = first, 1 = second
+
+    u32 address_left;
+    u32 address_right;
+    u32 stride;    // maps to 0x1EF00X90 ?
+    u32 format;    // maps to 0x1EF00X70 ?
+    u32 shown_fb;  // maps to 0x1EF00X78 ?
+    u32 unknown;
+};
+static_assert(sizeof(FrameBufferInfo) == 0x1c, "Struct has incorrect size");
+
 /// GSP command
 struct Command {
     BitField<0, 8, CommandId> id;