misc: add sl28cpld base driver

Add a multi-function device driver which will probe its children and
provides methods to access the device.

Signed-off-by: Michael Walle <michael@walle.cc>
[Rebased]
Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index fb171e0..8b3870f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1161,6 +1161,11 @@
 T:	git https://source.denx.de/u-boot/custodians/u-boot-sh.git
 F:	arch/sh/
 
+SL28CLPD
+M:	Michael Walle <michael@walle.cc>
+S:	Maintained
+F:	drivers/misc/sl28cpld.c
+
 SPI
 M:	Jagan Teki <jagan@amarulasolutions.com>
 S:	Maintained