devicetree-bindings: Add vendor entry for Smart Battery Systems

Signed-off-by: Rhyland Klein <rklein@nvidia.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -32,6 +32,7 @@ powervr	Imagination Technologies
 qcom	Qualcomm, Inc.
 ramtron	Ramtron International
 samsung	Samsung Semiconductor
+sbs	Smart Battery System
 schindler	Schindler
 simtek
 sirf	SiRF Technology, Inc.