powerc/mm: try VMA lock-based page fault handling first

Attempt VMA lock-based page fault handling first, and fall back to the
existing mmap_lock-based handling if that fails.  Copied from "x86/mm: try
VMA lock-based page fault handling first"

[ldufour@linux.ibm.com: powerpc/mm: fix mmap_lock bad unlock]
  Link: https://lkml.kernel.org/r/20230306154244.17560-1-ldufour@linux.ibm.com
  Link: https://lore.kernel.org/linux-mm/842502FB-F99C-417C-9648-A37D0ECDC9CE@linux.ibm.com
Link: https://lkml.kernel.org/r/20230227173632.3292573-32-surenb@google.com


Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Cc: Sachin Sant <sachinp@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>