Revert "f2fs: fix race in between GC and atomic open"

This reverts commit 2e405acc.

This is a preparation change for merging android-4.14 commit
73421a43 into msm-4.14 branch.
The reverted change is committed already as:

67226fb5 f2fs: fix race in between GC and atomic open

Conflicts:
	fs/f2fs/file.c

Change-Id: I98ceccaf2b738bf0660ec519ee2b4d4536c462d7
Signed-off-by: Blagovest Kolenichev <bkolenichev@codeaurora.org>