of: add vendor prefix for SMSC

Add a vendor prefix for Standard Microsystems Corporation, now part of
Microchip.
Signed-off-by: Florian Vaussard <florian.vaussard@epfl.ch>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -80,6 +80,7 @@ sil	Silicon Image
 silabs	Silicon Laboratories
 simtek
 sirf	SiRF Technology, Inc.
+smsc	Standard Microsystems Corporation
 snps 	Synopsys, Inc.
 spansion	Spansion Inc.
 st	STMicroelectronics