Add API to get min/max rail voltage configured from platform for given rails. This will help to set the pad voltage based on platform specific power tree. bug 200083043 Change-Id: I054734ca2a25b5c830525e27ab22e43534f67351 Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com> Reviewed-on: http://git-master/r/712001 (cherry picked from commit c0d1de0da091132d037e1bb32f2ee09b5c00369b) Reviewed-on: http://git-master/r/1119836 Signed-off-by: Thomas Makin <halorocker89@gmail.com>