ANDROID: f2fs: fix bad merge resolutions

The encrypt+casefold support needed to be adjusted following refactoring
of f2fs filename handing upstream.  Also, the upstream change to
f2fs_d_compare() needed to be moved to generic_ci_d_compare().  See
http://aosp/1341990 and also the other branches like android-5.4-stable.

Also, a call f2fs_set_bio_crypt_ctx() went missing.

Fixes: 8912845e ("Merge 42612e77 ("Merge tag 'f2fs-for-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs"

) into android-mainline")
Change-Id: Icd92029bab74e161497a1f03201826a737955725
Signed-off-by: Eric Biggers <ebiggers@google.com>