mips: use object_new() instead of gnew()+object_initialize()

object_initialize() is intended for inplace initialization of
objects, but here it's first allocated with g_new0() and then
initialized with object_initialize(). QEMU already has API
to do this (object_new), so do object creation with suitable
for usecase API.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <1507211474-188400-36-git-send-email-imammedo@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
