regulator: twl: add twl6030 get_status

Current get_status logic does not support 6030 get_status.
The logic for 4030 is not reusable for 6030 as the status
check for 6030 now depends on the new CFG_STATE register.
We hence rename the old get_status as being specific to
4030 and remove the redundant check for the same.

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Saquib Herman <saquib@ti.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@vega.(none)>