Add OAEP placeholders in asymmetric encrypt/decrypt

Replace PSS placeholders by OAEP placeholders. PSS is a signature
algorithm, not an encryption algorithm.

Fix typo in PSA_ALG_IS_RSA_OAEP_MGF1.
diff --git a/include/psa/crypto.h b/include/psa/crypto.h
index 0840494..db5b5f6 100755
--- a/include/psa/crypto.h
+++ b/include/psa/crypto.h
@@ -336,7 +336,7 @@
 #define PSA_ALG_RSA_OAEP_MGF1(hash_alg)                             \
     (PSA_ALG_RSA_OAEP_MGF1_RAW | ((hash_alg) & PSA_ALG_HASH_MASK))
 #define PSA_ALG_IS_RSA_OAEP_MGF1(alg)                               \
-    (((alg) & ~PSA_ALG_HASH_MASK) == PSA_ALG_RSA_OAEP_MGF1_RAW)
+    (((alg) & ~PSA_ALG_HASH_MASK) == PSA_ALG_RSA_OAEP_MGF1_BASE)
 #define PSA_ALG_RSA_GET_HASH(alg)                                       \
     (((alg) & PSA_ALG_HASH_MASK) | PSA_ALG_CATEGORY_HASH)