MISRA: Reduce the number of violations for MC3R1.R12.1

According to MC3R1.R12.1 the precedence
of operators within expressions should be made explicit.

Change-Id: Ia82d28dc437f83bba995cb75dff0d1282d3b3157
Signed-off-by: Elena Uziunaite <elena.uziunaite@arm.com>
Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com>
diff --git a/interface/src/tfm_crypto_api.c b/interface/src/tfm_crypto_api.c
index 65eae46..4fc4eca 100644
--- a/interface/src/tfm_crypto_api.c
+++ b/interface/src/tfm_crypto_api.c
@@ -1005,7 +1005,7 @@
 
     size_t out_len = IOVEC_LEN(out_vec);
 
-    if (ciphertext == NULL || ciphertext_size == 0) {
+    if ((ciphertext == NULL) || (ciphertext_size == 0)) {
         out_len--;
     }
     if ((out_len == 3) && (ciphertext_length == NULL)) {
@@ -1056,7 +1056,7 @@
 
     size_t out_len = IOVEC_LEN(out_vec);
 
-    if (plaintext == NULL || plaintext_size == 0) {
+    if ((plaintext == NULL) || (plaintext_size == 0)) {
         out_len--;
     }
     if ((out_len == 2) && (plaintext_length == NULL)) {