ANDROID: mm: Set PAGE_BLOCK_ORDER to 8 when ARM64_16K_PAGES

This config will allow the 16kb page size kernels to have the
same CMA_MIN_ALIGNMENT_BYTES that 4k kernels. This means that
the CMA configs for the drivers won't have to change.

Note: This change is needed to avoid breaking old kernel
builds.

Bug: 424212284
Bug: 375647879
Bug: 355449177
Bug: 418282543
Test: tools/bazel run //common:kernel_aarch64_dist
      tools/bazel run //common:kernel_aarch64_16k_dist
      tools/bazel run //common:kernel_x86_64_dist
Change-Id: Icbfcab0d7e5ba18b3fc35c1186ef79e82f3e7ab1
Signed-off-by: Juan Yescas <jyescas@google.com>