unicore32: replace uc32_cpu_init() with cpu_generic_init()

it's just a wrapper, drop it and use cpu_generic_init() directly

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <1503592308-93913-25-git-send-email-imammedo@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>