fusefs: fix some bugs updating atime during close

fusefs: fix some bugs updating atime during close

When using cached attributes, we must update a file's atime during
close, if it has been read since the last attribute refresh.  But,

* Don't update atime if we lack write permissions to the file or if the
  file system is readonly.
* If the daemon fails our atime update request for any reason, don't
  report this as a failure for VOP_CLOSE.

PR:		270749
Reported by:	Jamie Landeg-Jones <jamie@catflap.org>
MFC after:	1 week
Sponsored by:	Axcient
Reviewed by:	pfg
Differential Revision: https://reviews.freebsd.org/D41925