regulator: tps65218: do not disable DCDC3 during poweroff on broken PMICs

Some versions of tps65218 do not seem to support poweroff modes properly
if DCDC3 regulator is shut-down. Thus, keep it enabled even during
poweroff if the version info matches the broken silicon revision.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Keerthy <j-keerthy@ti.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>