nubus: Rename class type checking macros

nubus: Rename class type checking macros

Rename the existing class type checking macros to be consistent
with the type name and instance type checking macro.  Use a
NUBUS_MACFB prefix instead of MACFB_NUBUS.

This will make future conversion to OBJECT_DECLARE* easier.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Acked-by: Laurent Vivier <laurent@vivier.eu>
Tested-By: Roman Bolshakov <r.bolshakov@yadro.com>
Message-Id: <20200825192110.3528606-44-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>