ARM: dts: imx6qdl-apalis: Fix poweroff on Apalis iMX6

commit 83964a29 upstream.

The current solution for powering off the Apalis iMX6 is not functioning
as intended. To resolve this, it is necessary to power off the
vgen2_reg, which will also set the POWER_ENABLE_MOCI signal to a low
state. This ensures the carrier board is properly informed to initiate
its power-off sequence.

The new solution uses the regulator-poweroff driver, which will power
off the regulator during a system shutdown.

Cc: <stable@vger.kernel.org>
Fixes: 4eb56e26 ("ARM: dts: imx6q-apalis: Command pmic to standby for poweroff")
Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>