microblaze: replace cpu_mb_init() with cpu_generic_init()

microblaze: replace cpu_mb_init() with cpu_generic_init()

cpu_mb_init() always falls back to TYPE_MICROBLAZE_CPU object
regardless of cpu_model. Put fallback logic into
mb_cpu_class_by_name() which would translate any cpu_model
into TYPE_MICROBLAZE_CPU class and replace cpu_mb_init()
with cpu_generic_init().

Signed-off-by: Igor Mammedov <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Message-Id: <1503592308[email protected]>
Signed-off-by: Eduardo Habkost <[email protected]>