Turned B_RESTORE_HELD_BATTLE_ITEMS into a non-boolean config (#4402)

* Corrected the comment description of B_RESTORE_HELD_BATTLE_ITEMS

* Made B_RESTORE_HELD_BATTLE_ITEMS a non-boolean config

include/config/battle.h

@@ -152,7 +152,7 @@
 #define B_X_ITEMS_BUFF              GEN_LATEST // In Gen7+, the X Items raise a stat by 2 stages instead of 1.
 #define B_MENTAL_HERB               GEN_LATEST // In Gen5+, the Mental Herb cures Taunt, Encore, Torment, Heal Block, and Disable in addition to Infatuation from before.
 #define B_TRAINERS_KNOCK_OFF_ITEMS  TRUE       // If TRUE, trainers can steal/swap your items (non-berries are restored after battle). In vanilla games trainers cannot steal items.
-#define B_RESTORE_HELD_BATTLE_ITEMS TRUE       // In Gen9 all non berry items are restored after battle.
+#define B_RESTORE_HELD_BATTLE_ITEMS GEN_LATEST // In Gen9, all non-berry items are restored after battle.
 #define B_SOUL_DEW_BOOST            GEN_LATEST // In Gens3-6, Soul Dew boosts Latis' Sp. Atk and Sp. Def. In Gen7+ it boosts the power of their Psychic and Dragon type moves instead.
 #define B_NET_BALL_MODIFIER         GEN_LATEST // In Gen7+, Net Ball's catch multiplier is x5 instead of x3.
 #define B_DIVE_BALL_MODIFIER        GEN_LATEST // In Gen4+, Dive Ball's effectiveness increases by when Surfing or Fishing.

src/battle_main.c

@@ -5742,7 +5742,7 @@ static void HandleEndTurn_FinishBattle(void)
             TestRunner_Battle_AfterLastTurn();
         BeginFastPaletteFade(3);
         FadeOutMapMusic(5);
-        if (B_TRAINERS_KNOCK_OFF_ITEMS == TRUE || B_RESTORE_HELD_BATTLE_ITEMS == TRUE)
+        if (B_TRAINERS_KNOCK_OFF_ITEMS == TRUE || B_RESTORE_HELD_BATTLE_ITEMS >= GEN_9)
             TryRestoreHeldItems();
 
         // Undo Dynamax HP multiplier before recalculating stats.

src/battle_util.c

@@ -10837,7 +10837,7 @@ void TryRestoreHeldItems(void)
 
     for (i = 0; i < PARTY_SIZE; i++)
     {
-        if (B_RESTORE_HELD_BATTLE_ITEMS == TRUE || gBattleStruct->itemLost[i].stolen)
+        if (B_RESTORE_HELD_BATTLE_ITEMS >= GEN_9 || gBattleStruct->itemLost[i].stolen)
         {
             lostItem = gBattleStruct->itemLost[i].originalItem;
             if (lostItem != ITEM_NONE && ItemId_GetPocket(lostItem) != POCKET_BERRIES)