arm64: dts: apq8096-db820c: never disable regulator on LS expansion

1.8v regulator on LS expansion should not be disabled anytime to comply
with 96boards spec. So make this explicit with always-on flag.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>