crypto: atmel - only treat EBUSY as transient if backlog

commit 1606043f214f912a52195293614935811a6e3e53 upstream.

The Atmel SHA driver was treating -EBUSY as indication of queueing
to backlog without checking that backlog is enabled for the request.

Fix it by checking request flags.

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>