kernel: update yaffs code to the latest version

Use the latest version of the yaffs code. Fetched from the
yaffs2 git tree and it is based on the following commit:

commit 7e5cf0fa1b694f835cdc184a8395b229fa29f9ae
Author: Charles Manning <cdhmanning@gmail.com>
Date: Thu Aug 7 11:25:05 2014 +1200

yaffs-direct: Basic tests. Add lpthread flag for background gc support

Signed-off-by: Charles Manning <cdhmanning@gmail.com>

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@45188 3c298f89-4303-0410-b956-a3cf2f4a3e73

kernel: update yaffs code

Use the latest version of the yaffs code. Fetched from the
yaffs2 git tree and it is based on the following commit:

commit bc76682d93955cfb33051beb503ad9f8a5450578
Merge: 3a8580e ffa781d
Author: Charles Manning <cdhmanning@gmail.com>
Date: Thu Jul 11 17:46:25 2013 +1200

Merge branch 'master' of ssh://www.aleph1.co.uk/home/aleph1/git/yaffs2

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39084 3c298f89-4303-0410-b956-a3cf2f4a3e73