logcatd: unset pinning log files

commit 5327d931 ("logcatd: fallocate and fadvise to logcat files")
introduced pinning log files in order to avoid f2fs fragmentation.

But, logcatd does not guarantee to write data within fallocated 2MB space.
So, we can see some bytes written beyond 2MB boundary which results in
pinning small chunks across the filesystem. This makes F2FS GC have to unset
the pinning blocks via GC loop. If this happens during checkpoint=disable
at booting time, we can see long delay to mount /data accordingly.

Bug: 136483670
Bug: 137180754
Bug: 149418646
Fixes: 5327d931 ("logcatd: fallocate and fadvise to logcat files")
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
Change-Id: I986221d6d1da9b8e46e63d1be98ddf0ce4cb099f