acpi: Fix BERT size_t printf format error

Fix compilation on GCC 10.2.1 and address the underlying issue. The
printf format specifier for a size_t type is z.

Change-Id: Ieb1db6c0c3eb4947bd3617e418bac238b70ec08f
Signed-off-by: Benjamin Doron <benjamin.doron00@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50051
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/arch/x86/acpi_bert_storage.c

@@ -200,7 +200,7 @@ void *new_cper_fw_error_crashlog(acpi_generic_error_status_t *status, size_t cl_
 {
 	void *cl_data = bert_allocate_storage(cl_size);
 	if (!cl_data) {
-		printk(BIOS_ERR, "Error: Crashlog entry (size %lu) would exceed available region\n",
+		printk(BIOS_ERR, "Error: Crashlog entry (size %zu) would exceed available region\n",
 			cl_size);
 		return NULL;
 	}