ACPI / tables: Check if id is NULL in acpi_table_parse()

strncmp() does not check if the params are NULL. In acpi_table_parse(),
if @id is NULL, the kernel will panic.

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/tables.c

@@ -293,7 +293,7 @@ int __init acpi_table_parse(char *id, acpi_tbl_table_handler handler)
 	if (acpi_disabled)
 		return -ENODEV;
 
-	if (!handler)
+	if (!id || !handler)
 		return -EINVAL;
 
 	if (strncmp(id, ACPI_SIG_MADT, 4) == 0)