pm: cpupower: bench: Prevent NULL dereference on malloc failure

If malloc returns NULL due to low memory, 'config' pointer can be NULL.
Add a check to prevent NULL dereference.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Zhongqiu Han <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/power/cpupower/bench/parse.c

···
 struct config *prepare_default_config()
 {
 	struct config *config = malloc(sizeof(struct config));
+	if (!config) {
+		perror("malloc");
+		return NULL;
+	}
 
 	dprintf("loading defaults\n");