Revert "ANDROID: Revert "arm64: move ELF_ET_DYN_BASE to 4GB / 4MB""

This reverts commit 031af365.

ASan can handle the new memory layout in Android P and later, which
means this change can be reverted in 4.14.

Bug: 67425063
Signed-off-by: Evgenii Stepanov <eugenis@google.com>
Change-Id: I1b09210c521ce65bbdc1e9cdaca2b5e66e097789