[CRYPTO] tcrypt: Forbid tcrypt from being built-in

It makes no sense to build tcrypt into the kernel.  In fact, now that
the driver init function's return status is being checked, it is in
fact harmful to do so.

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

crypto/Kconfig

@@ -337,7 +337,7 @@ config CRYPTO_CRC32C
 
 config CRYPTO_TEST
 	tristate "Testing module"
-	depends on CRYPTO
+	depends on CRYPTO && m
 	help
 	  Quick & dirty crypto test module.