Simplify the encoding of key agreement algorithms

Get rid of "key selection" algorithms (of which there was only one:
raw key selection).

Encode key agreement by combining a raw key agreement with a KDF,
rather than passing the KDF as an argument of a key agreement macro.
diff --git a/include/psa/crypto_extra.h b/include/psa/crypto_extra.h
index 7d89fbf..a0eac4d 100644
--- a/include/psa/crypto_extra.h
+++ b/include/psa/crypto_extra.h
@@ -176,6 +176,8 @@
                                 size_t label_length,
                                 size_t capacity);
 
+/* FIXME Deprecated. Remove this as soon as all the tests are updated. */
+#define PSA_ALG_SELECT_RAW                      ((psa_algorithm_t)0x31000001)
 
 #ifdef __cplusplus
 }