fscrypt: don't clear flags on crypto transform

fscrypt is clearing the flags on the crypto_skcipher it allocates for
each inode.  But, this is unnecessary and may cause problems in the
future because it will even clear flags that are meant to be internal to
the crypto API, e.g. CRYPTO_TFM_NEED_KEY.

Remove the unnecessary flag clearing.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>