[AArch64] Add INITIALIZE_PASS macros to AArch64A57FPLoadBalancing.

These are needed so this pass will produce output when
e.g. -print-after-all is used.

Phabricator Review: http://reviews.llvm.org/D7264
Patch by Geoff Berry <gberry@codeaurora.org>!

llvm-svn: 227506