aries | p1: staging: zram: simplify num_devices paramater

Simplify dealing with num_devices when initializing zram.
Also cleanup some of the output messages.

Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Humberto Borba <humberos@gmail.com>

Change-Id: I129d72aa894c9608dafff03631d1da2e31c6857e