nds32: switch to generic version of pte allocation

nds32: switch to generic version of pte allocation

The nds32 implementation of pte_alloc_one_kernel() differs from the
generic in the use of __GFP_RETRY_MAYFAIL flag, which is removed after the
conversion.

The nds32 version of pte_alloc_one() missed the call to
pgtable_page_ctor() and also used __GFP_RETRY_MAYFAIL.  Switching it to
use generic __pte_alloc_one() for the PTE page allocation ensures that
page table constructor is run and the user page tables are allocated with
__GFP_ACCOUNT.

The conversion to the generic version of pte_free_kernel() removes the
NULL check for pte.

The pte_free() version on nds32 is identical to the generic one and can be
simply dropped.

Link: http://lkml.kernel.org/r/1557296232-15361-10-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Guo Ren <ren_guo@c-sky.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>