ACPI: use macro to replace hard number

Impact: cleanup

Use MACRO for rev 3 fadt id instead of 3 directly.
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLen Brown <len.brown@intel.com>

drivers/acpi/tables/tbfadt.c

@@ -304,7 +304,7 @@ static void acpi_tb_convert_fadt(void)
 	 * The ACPI 1.0 reserved fields that will be zeroed are the bytes located at
 	 * offset 45, 55, 95, and the word located at offset 109, 110.
 	 */
-	if (acpi_gbl_FADT.header.revision < 3) {
+	if (acpi_gbl_FADT.header.revision < FADT2_REVISION_ID) {
 		acpi_gbl_FADT.preferred_profile = 0;
 		acpi_gbl_FADT.pstate_control = 0;
 		acpi_gbl_FADT.cst_control = 0;