simplefb: print some info about the registered fb

This is similar to the output printed by efifb.

Signed-off-by: Tom Gundersen <teg@jklm.no>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>