regulator: max77802: set opmode to normal if off is read from hw

The max77802 driver reads the default operating mode (opmode)
set for regulators when enabled from the hardware registers.

But if a regulator is disabled and the system warm restarted,
the hardware reports OFF as the opmode so the regulator is
not enabled. Default to operating mode NORMAL if OFF is read
from the hardware register.

Reported-by: Yuvaraj Cd <yuvaraj.lkml@gmail.com>
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Tested-by: Yuvaraj Kumar CD <yuvaraj.cd@samsung.com>
Signed-off-by: Mark Brown <broonie@linaro.org>