test: cmocka: src: avoid NULL comparison

Replace NULL comparison with boolean negation. Issue found using
Coccinelle.

Signed-off-by: Payal Kshirsagar <payalskshirsagar1234@gmail.com>

test/cmocka/src/audio/pipeline/pipeline_new.c

@@ -22,7 +22,7 @@ static int setup(void **state)
 
 	pipeline_posn_init(sof_get());
 
-	if (pipeline_data == NULL)
+	if (!pipeline_data)
 		return -1;
 
 	struct sof_ipc_pipe_new pipe_desc = { .core = 1, .priority = 2 };

test/cmocka/src/list/list_item_append.c

@@ -23,7 +23,7 @@ static int setup(void **state)
 {
 	struct test_data *data = malloc(sizeof(struct test_data));
 
-	if (data == NULL)
+	if (!data)
 		return -1;
 
 	data->head = malloc(sizeof(struct list_item));

test/cmocka/src/list/list_item_del.c

@@ -23,7 +23,7 @@ static int setup(void **state)
 {
 	struct test_data *data = malloc(sizeof(struct test_data));
 
-	if (data == NULL)
+	if (!data)
 		return -1;
 
 	data->head = malloc(sizeof(struct list_item));

test/cmocka/src/list/list_item_is_last.c

@@ -23,7 +23,7 @@ static int setup(void **state)
 {
 	struct test_data *data = malloc(sizeof(struct test_data));
 
-	if (data == NULL)
+	if (!data)
 		return -1;
 
 	data->head = malloc(sizeof(struct list_item));

test/cmocka/src/list/list_item_prepend.c

@@ -23,7 +23,7 @@ static int setup(void **state)
 {
 	struct test_data *data = malloc(sizeof(struct test_data));
 
-	if (data == NULL)
+	if (!data)
 		return -1;
 
 	data->head = malloc(sizeof(struct list_item));