Add break for default cases

Visual Studio has an option to search all files in a solution, so I
did a search in there for "default:" looking for any missing break
statements.

I've left out default statements that return something, and that throw
something, even if via ThrowInvalidType. UNREACHABLE leads towards throw

R_THROW macro leads towards a return

src/video_core/textures/decoders.cpp

@@ -170,6 +170,7 @@ void Swizzle(std::span<u8> output, std::span<const u8> input, u32 bytes_per_pixe
 #undef BPP_CASE
     default:
         ASSERT_MSG(false, "Invalid bytes_per_pixel={}", bytes_per_pixel);
+        break;
     }
 }
 
@@ -217,6 +218,7 @@ void SwizzleSubrect(std::span<u8> output, std::span<const u8> input, u32 bytes_p
 #undef BPP_CASE
     default:
         ASSERT_MSG(false, "Invalid bytes_per_pixel={}", bytes_per_pixel);
+        break;
     }
 }
 
@@ -240,6 +242,7 @@ void UnswizzleSubrect(std::span<u8> output, std::span<const u8> input, u32 bytes
 #undef BPP_CASE
     default:
         ASSERT_MSG(false, "Invalid bytes_per_pixel={}", bytes_per_pixel);
+        break;
     }
 }