Fix other warnings

Most were harmless, but the change to ACCESS_ONCE from volatile
cast is probably useful.
Expanding macro, we basically went from:
    m = (volatile struct sdma_vl_map *)dd->sdma_map;
to
    m = *(volatile struct sdma_vl_map **)&(dd->sdma_map);
i.e. the explicit lookup is at a different level.

arch/x86_64/kernel/include/ihk/atomic.h

@@ -133,7 +133,7 @@ static inline void ihk_atomic64_inc(ihk_atomic64_t *v)
  * Note 2: xchg has side effect, so that attribute volatile is necessary,
  *	  but generally the primitive is invalid, *ptr is output argument. --ANK
  */
-#define __xg(x) ((volatile long *)(x))
+#define __xg(x) ((volatile typeof(x))(x))
 
 #define xchg4(ptr, x)						\
 ({									\