arm64: dts: apq8016-sbc: make 1.8v available on LS expansion

96boards mezzanine boards on LS expansion require 1.8v as per 96boards
specifications, so enable the corresponding regulators and make them
always-on.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>