MLK-12675 ARM: dts: imx: keep RTC enabled for software poweroff
SRTC needs to be kept enabled during system poweroff,
SNVS_LP control register bit 0 SRTC_ENV must be set
to enable RTC, for software poweroff, kernel just
read the register offset and value from dtb and write
to SNVS_LP control register to poweroff system, need
to make sure bit 0 SRTC_ENV is set to enable RTC during
system poweroff.
Previous setting did NOT enable it which will cause
RTC stop running if using software poweroff.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>