ACPICA: Tables: Cleanup RSDP signature codes.

This patch introduces new macors to handle RSDP signature and cleans up the
affected codes.  Lv Zheng.
Some updates are only used for ACPICA utilities which are not shipped in
the kernel yet.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/acpica/tbxfroot.c b/drivers/acpi/acpica/tbxfroot.c
index 948c95e..1c95fabb 100644
--- a/drivers/acpi/acpica/tbxfroot.c
+++ b/drivers/acpi/acpica/tbxfroot.c
@@ -68,8 +68,7 @@
 	 * Note: Sometimes there exists more than one RSDP in memory; the valid
 	 * RSDP has a valid checksum, all others have an invalid checksum.
 	 */
-	if (ACPI_STRNCMP((char *)rsdp->signature, ACPI_SIG_RSDP,
-			 sizeof(ACPI_SIG_RSDP) - 1) != 0) {
+	if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) {
 
 		/* Nope, BAD Signature */