ubifs: Don't encrypt special files on creation

When a new inode is created, we check if the containing folder has a encryption
policy set and inherit that. This should however only be done for regular
files, links and subdirectories. Not for sockes fifos etc.

Fixes: d475a507 ("ubifs: Add skeleton for fscrypto")
Cc: stable@vger.kernel.org
Signed-off-by: David Gstir <david@sigma-star.at>
Signed-off-by: Richard Weinberger <richard@nod.at>