Removed trailing spaces in the most relevant files

Command used for the job:
egrep -rl ' $' --include *.c --include *.h --include  *.s --include  *.inc --include  *.txt *  | xargs sed -i 's/\s\+$//g'

Credits to Grant Murphy from Stack Overflow.

src/menu_helpers.c

@@ -280,7 +280,7 @@ bool8 IsHoldingItemAllowed(u16 itemId)
     // Enigma Berry can't be held in link areas
     if (itemId != ITEM_ENIGMA_BERRY)
         return TRUE;
-    else if (gSaveBlock1Ptr->location.mapGroup == MAP_GROUP(TRADE_CENTER) 
+    else if (gSaveBlock1Ptr->location.mapGroup == MAP_GROUP(TRADE_CENTER)
           && gSaveBlock1Ptr->location.mapNum == MAP_NUM(TRADE_CENTER))
         return FALSE;
     else if (InUnionRoom() != TRUE)