riscv/syscall: Fix sched_note instrumentation for BUILD_KERNEL

The sched_note calls were missing from riscv_perform_syscall().

arch/risc-v/src/common/supervisor/riscv_perform_syscall.c

@@ -65,6 +65,10 @@ void *riscv_perform_syscall(uintreg_t *regs)
 
       addrenv_switch(NULL);
 #endif
+      /* Update scheduler parameters */
+
+      nxsched_suspend_scheduler(g_running_tasks[this_cpu()]);
+      nxsched_resume_scheduler(tcb);
 
       /* Record the new "running" task.  g_running_tasks[] is only used by
        * assertion logic for reporting crashes.