ANDROID: mm: add missing check in the backport for handling faults under VMA lock

While backporting, a check for vma locking inside do_wp_page() was
missed. Add it.

Fixes: 3ebafb7b ("BACKPORT: FROMGIT: mm: handle faults that merely update the accessed bit under the VMA lock")
Bug: 293665307
Change-Id: Ibd7f21ae8fec7b8edc6e3d88954714b5fad41516
Signed-off-by: Suren Baghdasaryan <surenb@google.com>