xtensa: switch to generic version of pte allocation

xtensa: switch to generic version of pte allocation

xtensa clears PTEs during allocation of the page tables and pte_clear()
sets the PTE to a non-zero value.  Splitting ptes_clear() helper out of
pte_alloc_one() and pte_alloc_one_kernel() allows reuse of base generic
allocation methods (__pte_alloc_one() and __pte_alloc_one_kernel()) and
the common GFP mask for page table allocations.

The pte_free() and pte_free_kernel() implementations on xtensa are
identical to the generic ones and can be dropped.

[[email protected]: xtensa: fix closing endif comment]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Mike Rapoport <[email protected]>
Signed-off-by: Max Filippov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Pekka Enberg <[email protected]>
Cc: Abdul Haleem <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Max Filippov <[email protected]>
Cc: Peter Zijlstra (Intel) <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Stafford Horne <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>