ACPICA: allow Load(OEMx) tables

HP and Hitachi machines have been implemented with SSDT's
that use the "OEMx" signatures.  But upon Load, ACPICA is rejecting
these tables because they are not using the "SSDT" signature.

ACPI Error (tbinstal-0134): Table has invalid signature [OEMx], must be SSDT...
Signed-off-by: NLen Brown <len.brown@intel.com>

drivers/acpi/tables/tbinstal.c

@@ -123,14 +123,14 @@ acpi_tb_add_table(struct acpi_table_desc *table_desc,
 		}
 	}
 
-	/* The table must be either an SSDT or a PSDT */
+	/* The table must be either an SSDT or a PSDT or an OEMx */
 
 	if ((!ACPI_COMPARE_NAME(table_desc->pointer->signature, ACPI_SIG_PSDT))
 	    &&
-	    (!ACPI_COMPARE_NAME(table_desc->pointer->signature, ACPI_SIG_SSDT)))
-	{
+	    (!ACPI_COMPARE_NAME(table_desc->pointer->signature, ACPI_SIG_SSDT))
+	    && (strncmp(table_desc->pointer->signature, "OEM", 3))) {
 		ACPI_ERROR((AE_INFO,
-			    "Table has invalid signature [%4.4s], must be SSDT or PSDT",
+			    "Table has invalid signature [%4.4s], must be SSDT, PSDT or OEMx",
 			    table_desc->pointer->signature));
 		return_ACPI_STATUS(AE_BAD_SIGNATURE);
 	}