Revert "f2fs: support 3.4"

This reverts commit 15e1d7d73d833ed00632960322f1217462b7a0e3.
Revert "fs: import f2fs from git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git (branch dev)"

This reverts commit b913a28eba136c2f90ece758e7a158dcd2fc81e6.
Revert "Revert "FS: import F2FS""

This reverts commit 432c43b3e5676fefd13b89a35ea42774ddf49320.