removed a #include of a kernel header

Turns out it's not actually necessary and something clang did (didn't
use customized versions of the kernel headers like gcc might?) made
stuff not work with it.
diff --git a/aos/linux_code/init.cc b/aos/linux_code/init.cc
index d05df77..e8bcba1 100644
--- a/aos/linux_code/init.cc
+++ b/aos/linux_code/init.cc
@@ -6,7 +6,6 @@
 #include <errno.h>
 #include <sched.h>
 #include <sys/resource.h>
-#include <asm-generic/resource.h>  // for RLIMIT_RTTIME
 #include <sys/types.h>
 #include <unistd.h>
 #include <stdlib.h>