Revert "FROMLIST: fs/buffer.c: Revoke LRU when trying to drop buffers"

This reverts commit 7d212a51.

This commit is superseded by commit a0a0b3f4 ("FROMLIST: mm: fs:
Invalidate BH LRU during page migration").

Conflicts:
    fs/buffer.c

1. In fs/buffer.c had to keep invalidate_bh_lrus_cpu() function that was
introduced in commit a0a0b3f4 as well as in the reverted commit.

Bug: 174118021
Signed-off-by: Chris Goldsworthy <cgoldswo@codeaurora.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I60d0a4e8beb35389727f29fea6ca4640ecee40a7