Fix max init value in functions to 1 (#36686)

- Changed the initial value of max to 1 within the function.
- If max is not updated during the for loop, it returns -1, which can cause an INTEGER_OVERFLOW
- By initializing max to 1, it ensures that if max is updated during the loop, the updated value is used.
- If no value is updated, it performs the -1 operation and updates to 0.

src/lib/dnssd/TxtFields.h

@@ -121,7 +121,7 @@ uint8_t GetCommissionerPasscode(const ByteSpan & value);
 
 constexpr size_t MaxKeyLen(TxtKeyUse use)
 {
-    size_t max = 0;
+    size_t max = 1;
     for (auto & info : Internal::txtFieldInfo)
     {
         if (use == info.use)
@@ -147,7 +147,7 @@ constexpr size_t TotalKeyLen(TxtKeyUse use)
 
 constexpr size_t MaxValueLen(TxtKeyUse use)
 {
-    size_t max = 0;
+    size_t max = 1;
     for (auto & info : Internal::txtFieldInfo)
     {
         if (use == info.use)