BACKPORT: f2fs: give priority to select unpinned section for foreground GC

Previously, during foreground GC, if victims contain data of pinned file,
it will fail migration of the data, and meanwhile i_gc_failures of that
pinned file may increase, and when it exceeds threshold, GC will unpin
the file, result in breaking pinfile's semantics.

In order to mitigate such condition, let's record and skip section which
has pinned file's data and give priority to select unpinned one.

Bug: 278486610
Signed-off-by: Chao Yu <chao.yu@oppo.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Chao Yu <chao@kernel.org>
(cherry picked from commit 8f84484a)
(cherry picked from https://android-review.googlesource.com/q/commit:7771fe887f137d6a1340922ffe0ce65fa44cf8eb)
Merged-In: I5477ba502254e3109c01e118301c99f6332c1da5
Change-Id: I5477ba502254e3109c01e118301c99f6332c1da5