UPSTREAM: f2fs: make LAZYTIME a mount option flag

Set LAZYTIME into sbi during parsing, and transfer it to the sb in
fill_super, so that an sb is not required during option parsing.

(Note: While lazytime is normally handled via mount flag in the vfs,
some f2fs users do expect to be able to use it as an explicit mount
option string via the mount syscall, so this option must remain.)

Change-Id: I0be13af32ae7e47a2dc462af9e6097a3ddbb6b35
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
(cherry picked from commit 9100adf3)