PMIC swbst regulator is used for the MikroBUS socket (pin +5V).

We have to set the regulator to "boot-on" and "always-on"
to output a voltage of 5V on this socket.
Signed-off-by: Pierre-Jean Texier <pjtexier@koncepto.io>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>