fix(p3io): Off-by-one error on assert

Buffers are allowed to have the exact size as the max defined
P3IO buffer size. Cutting it short by one byte causes this
to fail incorrectly when using the pure raw buffer structure

src/main/p3io/cmd.c

@@ -41,7 +41,7 @@ void p3io_resp_hdr_init(
 {
     log_assert(resp_hdr != NULL);
     log_assert(req_hdr != NULL);
-    log_assert(nbytes < P3IO_MAX_MESSAGE_SIZE);
+    log_assert(nbytes <= P3IO_MAX_MESSAGE_SIZE);
 
     /* Length byte in this packet format counts everything from the length
        byte onwards. The length byte itself occurs at the start of the frame. */