ARM: dts: msm: Add always-on flag for L12A on sa8195

As a temporary solution L12A need to be voted always on for system
stability, add the regulator flag for it.

Change-Id: Ibbaab444c7d651b1c80f64098a6edeeb881e7a51
Signed-off-by: Veera Vegivada <vvegivad@codeaurora.org>