Removes unused dropout switch macro

Eliminates the DROPOUT_SWITCH macro definition which was no longer needed in the codebase, simplifying the conditional compilation logic and reducing code complexity.

Author: LoserCheems

csrc/src/static_switch.h

@@ -26,16 +26,6 @@
     }                                           \
   }()
 
-#ifdef FLASHATTENTION_DISABLE_DROPOUT
-  #define DROPOUT_SWITCH(COND, CONST_NAME, ...) \
-  [&] {                                         \
-    constexpr static bool CONST_NAME = false;   \
-    return __VA_ARGS__();                       \
-  }()
-#else
-  #define DROPOUT_SWITCH BOOL_SWITCH
-#endif
-
 #ifdef FLASHATTENTION_DISABLE_UNEVEN_K
   #define EVENK_SWITCH(COND, CONST_NAME, ...)   \
   [&] {                                         \