crypto: mxs-dcp - Only set OTP_KEY bit for OTP key

While MXS_DCP_CONTROL0_OTP_KEY is set, the CRYPTO_KEY (DCP_PAES_KEY_OTP)
is used even if the UNIQUE_KEY (DCP_PAES_KEY_UNIQUE) is selected. This
is not clearly documented, but this implementation is consistent with
NXP's downstream kernel fork and optee_os.

Signed-off-by: Sven Schwermer <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/mxs-dcp.c

···
 		    MXS_DCP_CONTROL0_INTERRUPT |
 		    MXS_DCP_CONTROL0_ENABLE_CIPHER;
 
-	if (key_referenced)
-		/* Set OTP key bit to select the key via KEY_SELECT. */
-		desc->control0 |= MXS_DCP_CONTROL0_OTP_KEY;
-	else
+	if (!key_referenced)
 		/* Payload contains the key. */
 		desc->control0 |= MXS_DCP_CONTROL0_PAYLOAD_KEY;
+	else if (actx->key[0] == DCP_PAES_KEY_OTP)
+		/* Set OTP key bit to select the key via KEY_SELECT. */
+		desc->control0 |= MXS_DCP_CONTROL0_OTP_KEY;
 
 	if (rctx->enc)
 		desc->control0 |= MXS_DCP_CONTROL0_CIPHER_ENCRYPT;