f2fs: replace ktype default_attrs with default_groups

The kobj_type default_attrs field is being replaced by the
default_groups field. Replace the default_attrs fields in f2fs_sb_ktype
and f2fs_feat_ktype with default_groups. Use the ATTRIBUTE_GROUPS macro
to create f2fs_groups and f2fs_feat_groups.

Fixes: fef4129e ("f2fs: fix to be aware discard/preflush/dio command in is_idle()")
Signed-off-by: Kimberly Brown <kimbrownkd@gmail.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>