remove extra define for __NR_getrandom and add some comments
@@ -319,9 +319,7 @@ static ssize_t sysctl_random(char *buf, size_t buflen)
# define __NR_getrandom 352
# elif defined(__cris__)
# define __NR_getrandom 356
-# elif defined(__aarch64__)
-# define __NR_getrandom 278
-# else /* generic */
+# else /* generic (f.e. aarch64, loongarch, loongarch64) */
# define __NR_getrandom 278
# endif
# endif
