[ltr501] Fix clang-tidy sign comparison errors (#11057)

esphome/components/ltr501/ltr501.cpp

@@ -2,6 +2,7 @@
 #include "esphome/core/application.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
+#include <limits>
 
 using esphome::i2c::ErrorCode;
 
@@ -28,30 +29,30 @@ bool operator!=(const GainTimePair &lhs, const GainTimePair &rhs) {
 
 template<typename T, size_t size> T get_next(const T (&array)[size], const T val) {
   size_t i = 0;
-  size_t idx = -1;
+  size_t idx = std::numeric_limits<size_t>::max();
-  while (idx == -1 && i < size) {
+  while (idx == std::numeric_limits<size_t>::max() && i < size) {
     if (array[i] == val) {
       idx = i;
       break;
     }
     i++;
   }
-  if (idx == -1 || i + 1 >= size)
+  if (idx == std::numeric_limits<size_t>::max() || i + 1 >= size)
     return val;
   return array[i + 1];
 }
 
 template<typename T, size_t size> T get_prev(const T (&array)[size], const T val) {
   size_t i = size - 1;
-  size_t idx = -1;
+  size_t idx = std::numeric_limits<size_t>::max();
-  while (idx == -1 && i > 0) {
+  while (idx == std::numeric_limits<size_t>::max() && i > 0) {
     if (array[i] == val) {
       idx = i;
       break;
     }
     i--;
   }
-  if (idx == -1 || i == 0)
+  if (idx == std::numeric_limits<size_t>::max() || i == 0)
     return val;
   return array[i - 1];
 }