doc/devicetree: Add Aspeed and Tyan to vendor-prefixes

ASPEED Technology Inc is a fabless IC-design company.  Their web site
is http://www.aspeedtech.com/.

Tyan is a manufactuer of server and workstation platforms.

Signed-off-by: Joel Stanley <joel@jms.id.au>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -29,6 +29,7 @@ arm	ARM Ltd.
 armadeus	ARMadeus Systems SARL
 artesyn	Artesyn Embedded Technologies Inc.
 asahi-kasei	Asahi Kasei Corp.
+aspeed	ASPEED Technology Inc.
 atlas	Atlas Scientific LLC
 atmel	Atmel Corporation
 auo	AU Optronics Corporation
@@ -250,6 +251,7 @@ tplink	TP-LINK Technologies Co., Ltd.
 tronfy	Tronfy
 tronsmart	Tronsmart
 truly	Truly Semiconductors Limited
+tyan	Tyan Computer Corporation
 upisemi	uPI Semiconductor Corp.
 urt	United Radiant Technology Corporation
 usi	Universal Scientific Industrial Co., Ltd.