crypto: testmgr - WARN on test failure

Currently, by default crypto self-test failures only result in a
pr_warn() message and an "unknown" status in /proc/crypto.  Both of
these are easy to miss.  There is also an option to panic the kernel
when a test fails, but that can't be the default behavior.

A crypto self-test failure always indicates a kernel bug, however, and
there's already a standard way to report (recoverable) kernel bugs --
the WARN() family of macros.  WARNs are noisier and harder to miss, and
existing test systems already know to look for them in dmesg or via
/proc/sys/kernel/tainted.

Therefore, call WARN() when an algorithm fails its self-tests.

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