utils: bitarray: fix comparison of int of different signs

Clang 20.1.0 -Wsign-compare warning on int being compared with size_t
(unsigned int).

Signed-off-by: Alex Fabre <alex.fabre@rtone.fr>

Author: AlexFabre

lib/utils/bitarray.c

@@ -620,7 +620,7 @@ int sys_bitarray_find_nth_set(sys_bitarray_t *bitarray, size_t n, size_t num_bit
 	/* The bit we are looking for must be in the current bundle idx.
 	 * Find out the exact index of the bit.
 	 */
-	for (int j = 0; j <= bundle_bitness(bitarray) - 1; j++) {
+	for (size_t j = 0; j <= bundle_bitness(bitarray) - 1; j++) {
 		if (bitarray->bundles[idx] & mask & BIT(j)) {
 			if (--n <= 0) {
 				*found_at = idx * bundle_bitness(bitarray) + j;