Removed the vi format comments from the source

Vim users can use the [editorconfig plugin](https://github.com/editorconfig/editorconfig-vim) to automatically set tab spacing for the SDL coding style.

Fixes https://github.com/libsdl-org/SDL/issues/6903

src/atomic/SDL_atomic.c

@@ -303,5 +303,3 @@ void SDL_MemoryBarrierAcquireFunction(void)
 {
     SDL_MemoryBarrierAcquire();
 }
-
-/* vi: set ts=4 sw=4 expandtab: */

src/atomic/SDL_spinlock.c

@@ -206,5 +206,3 @@ void SDL_AtomicUnlock(SDL_SpinLock *lock)
     *lock = 0;
 #endif
 }
-
-/* vi: set ts=4 sw=4 expandtab: */