mm/powerpc: replace pXd_is_leaf() with pXd_leaf()

mm/powerpc: replace pXd_is_leaf() with pXd_leaf()

They're the same macros underneath.  Drop pXd_is_leaf(), instead always use
pXd_leaf().

At the meantime, instead of renames, drop the pXd_is_leaf() fallback
definitions directly in arch/powerpc/include/asm/pgtable.h.  because
similar fallback macros for pXd_leaf() are already defined in
include/linux/pgtable.h.

Link: https://lkml.kernel.org/r/20240305043750.93762-3-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>