This patch adds back MMC cover switch support in a way that
supports multiple slots.
Signed-off-by: Juha Yrjola <juha.yrjola@solidboot.com> Signed-off-by: Jarkko Lavinen <jarkko.lavinen@nokia.com> Signed-off-by: Carlos Eduardo Aguiar <carlos.aguiar@indt.org.br>