memory: of_memory: Silence uninitialized variable warning

Presumably we never use the default: case statement which prints a
warning message.  But my static checker complains that if we do, we will
hit an uninitialized variable warning.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>