Correct comment about mbedtls error codes

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/mbedtls/psa_util.h b/include/mbedtls/psa_util.h
index 32d20b5..f7ed2eb 100644
--- a/include/mbedtls/psa_util.h
+++ b/include/mbedtls/psa_util.h
@@ -348,8 +348,8 @@
     /* Error codes used by PSA crypto are in -255..-128, fitting in 16 bits. */
     int16_t psa_status;
     /* Error codes used by Mbed TLS are in one of the ranges
-     * -127..-1 (low-level) or (-128) * (128..511) (high-level),
-     * fitting in 16 bits. */
+     * -127..-1 (low-level) or -32767..-4096 (high-level with a low-level
+     * code optionally added), fitting in 16 bits. */
     int16_t mbedtls_error;
 } mbedtls_error_pair_t;