acpi: simplify updating header checksum

Use acpi_update_checksum() for updating ACPI table header checksum.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
diff --git a/lib/acpi/mcfg.c b/lib/acpi/mcfg.c
index 8b8a5bf..e21fe7c 100644
--- a/lib/acpi/mcfg.c
+++ b/lib/acpi/mcfg.c
@@ -57,7 +57,7 @@
 
 	/* (Re)calculate length and checksum */
 	header->length = (ulong)ctx->current - (ulong)mcfg;
-	header->checksum = table_compute_checksum(mcfg, header->length);
+	acpi_update_checksum(header);
 
 	acpi_add_table(ctx, mcfg);