change binary_string_parser for big-endian input

Signed-off-by: Kusumit Ghoderao <Kusumit.Ghoderao@silabs.com>
diff --git a/tests/suites/test_suite_psa_crypto.function b/tests/suites/test_suite_psa_crypto.function
index 6ac548e..6f528f1 100644
--- a/tests/suites/test_suite_psa_crypto.function
+++ b/tests/suites/test_suite_psa_crypto.function
@@ -301,7 +301,7 @@
     uint64_t result = 0;
     TEST_LE_U(bin_string->len, 8);
     for (size_t i = 0; i < bin_string->len; i++) {
-        result = result << 64 | bin_string->x[i];
+        result = result << 8 | bin_string->x[i];
     }
 exit:
     return result; /* returns 0 if len > 8 */