crypto: testmgr - remove panic_on_fail

The cryptomgr.panic_on_fail=1 kernel command-line parameter is not very
useful now that the tests have been fixed to WARN on failure, since
developers can just use panic_on_warn=1 instead.  There's no need for a
special option just for the crypto self-tests.  Remove it.

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