With IFUNC support in the kernel, we can finally get rid of our poor-man's ifunc for pmap, utilizing kobj. Since moea64 uses a second tier kobj as well, for its own private methods, this adds a second pmap install function (pmap_mmu_init()) to perform pmap 'post-install pre-bootstrap' initialization, before the IFUNCs get initialized. Reviewed by: bdragon