crypto: nx - don't abuse shash MAY_SLEEP flag

The nx driver uses the MAY_SLEEP flag in shash_desc::flags as an
indicator to not retry sending the operation to the hardware as many
times before returning -EBUSY.  This is bogus because (1) that's not
what the MAY_SLEEP flag is for, and (2) the shash API doesn't allow
failing if the hardware is busy anyway.

For now, just make it always retry the larger number of times.  This
doesn't actually fix this driver, but it at least makes it not use the
shash_desc::flags field anymore.  Then this field can be removed, as no
other drivers use it.

Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>