crypto: ccp - Validate the the error value used to index error messages

The error code read from the queue status register is only 6 bits wide,
but we need to verify its value is within range before indexing the error
messages.

Fixes: 81422bad ("crypto: ccp - Make syslog errors human-readable")
Cc: <stable@vger.kernel.org>
Reported-by: Cfir Cohen <cfir@google.com>
Signed-off-by: Gary R Hook <gary.hook@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>