acpi: simplify acpi_write_ssdt()

* Converting to void * is superfluous when calling memset().
* acpi_fill_header() already fills oem_table_id.

Fixes: d953137526cc ("x86: Move SSDT table to a writer function")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/lib/acpi/ssdt.c b/lib/acpi/ssdt.c
index 659c1aa..b140b4b 100644
--- a/lib/acpi/ssdt.c
+++ b/lib/acpi/ssdt.c
@@ -18,10 +18,9 @@
 	int ret;
 
 	ssdt = ctx->current;
-	memset((void *)ssdt, '\0', sizeof(struct acpi_table_header));
+	memset(ssdt, '\0', sizeof(struct acpi_table_header));
 
 	acpi_fill_header(ssdt, "SSDT");
-	memcpy(ssdt->oem_table_id, OEM_TABLE_ID, sizeof(ssdt->oem_table_id));
 	ssdt->revision = acpi_get_table_revision(ACPITAB_SSDT);
 	ssdt->aslc_revision = 1;
 	ssdt->length = sizeof(struct acpi_table_header);