The page tables are cached now, and given the significant speedup, I

The page tables are cached now, and given the significant speedup, I
don't think we'll ever go back.  So let's ditch the code that tries to
check and patch up incorrect memory attributes.

Also realize that pmap_clean_page(pg, FALSE) doesn't do anything
anymore so remove those calls and drop the 2nd argument from
pmap_clean_page(pg, TRUE) calls.

Last but not least, get rid of pmap_pte_init_generic() here.  The only
useful thing it did was setting pmap_copy_page_func() and
pmap_zero_page_func().

This diff should not introduce any change in behaviour.

ok visa@