dt-bindings: Add summit vendor id

Add vendor id for Summit microelectronics
for SMB347 charger.

Cc: John Stultz <john.stultz@linaro.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: NJonghwa Lee <jonghwa3.lee@samsung.com>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Myungjoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: NVinay Simha BN <simhavcs@gmail.com>
Signed-off-by: NRob Herring <robh@kernel.org>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -255,6 +255,7 @@ starry	Starry Electronic Technology (ShenZhen) Co., LTD
 startek	Startek
 ste	ST-Ericsson
 stericsson	ST-Ericsson
+summit	Summit microelectronics
 sunchip	Shenzhen Sunchip Technology Co., Ltd
 SUNW	Sun Microsystems, Inc
 swir	Sierra Wireless