dt-bindings: vendor-prefixes: Add Alps

Alps Electric Co., Ltd. is a japanese electronics company:
https://www.alps.com/



Signed-off-by: Nick Reitemeyer <nick.reitemeyer@web.de>
Reviewed-by: Stephan Gerhold <stephan@gerhold.net>
Tested-by: Stephan Gerhold <stephan@gerhold.net>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>