qdl: use correct printf modifier for size_t

printf uses z modifier to print size_t.

Also change d modifier to u, since size_t is unsigned.
(ssize_t is the signed version.)

Fixes build warning on 32-bit systems, e.g. ARMv7.
Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

firehose.c

@@ -310,7 +310,7 @@ static int firehose_configure(int fd, bool skip_storage_init)
 	}
 
 	if (qdl_debug) {
-		fprintf(stderr, "[CONFIGURE] max payload size: %ld\n",
+		fprintf(stderr, "[CONFIGURE] max payload size: %zu\n",
 			max_payload_size);
 	}