crypto: testmgr - Hide ENOENT errors

When a crypto algorithm with a higher priority is registered, it
kills the spawns of all lower-priority algorithms.  Thus it is to
be expected for an algorithm to go away at any time, even during
a self-test.  This is now much more common with asynchronous testing.

Remove the printk when an ENOENT is encountered during a self-test.
This is not really an error since the algorithm being tested is no
longer there (i.e., it didn't fail the test which is what we care
about).

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>