wifi: softirq: reduce ksoftirqd scheduled rate to improve TCP throughtput

PD#162113: improve ap62x8 rx tput

The reason why wifi TCP rx throughtput lower than kernel3.14 are as flollows:
On K3.14, RX has more time to work in ISR, but on K4.9, RX has more time to
work in kernel ksoftirqd thread, however, ksoftirqd has a very low priority.

On K4.9, a commit from upstream caused this difference, then revert it.

Revert "softirq: Let ksoftirqd do its job"

This reverts commit 4cd13c21b2.

Change-Id: I094232dad5dfddbcd94c35ec42a5e3302ed52459
Signed-off-by: libo <bo.li@amlogic.com>

kernel/softirq.c

@@ -27,6 +27,10 @@
 #include <linux/tick.h>
 #include <linux/irq.h>
 
+#ifndef CONFIG_AMLOGIC_MODIFY
+#define KSOFTIRQD_HIGH_RATE
+#endif
+
 #define CREATE_TRACE_POINTS
 #include <trace/events/irq.h>
 
@@ -81,12 +85,14 @@ static void wakeup_softirqd(void)
  * If ksoftirqd is scheduled, we do not want to process pending softirqs
  * right now. Let ksoftirqd handle this at its own rate, to get fairness.
  */
+#ifdef KSOFTIRQD_HIGH_RATE
 static bool ksoftirqd_running(void)
 {
 	struct task_struct *tsk = __this_cpu_read(ksoftirqd);
 
 	return tsk && (tsk->state == TASK_RUNNING);
 }
+#endif
 
 /*
  * preempt_count and SOFTIRQ_OFFSET usage:
@@ -335,8 +341,13 @@ asmlinkage __visible void do_softirq(void)
 
 	pending = local_softirq_pending();
 
-	if (pending && !ksoftirqd_running())
+#ifdef KSOFTIRQD_HIGH_RATE
+	if (pending && !ksoftirqd_running()) {
+#else
+	if (pending) {
+#endif
 		do_softirq_own_stack();
+	}
 
 	local_irq_restore(flags);
 }
@@ -362,9 +373,10 @@ void irq_enter(void)
 
 static inline void invoke_softirq(void)
 {
+#ifdef KSOFTIRQD_HIGH_RATE
 	if (ksoftirqd_running())
 		return;
-
+#endif
 	if (!force_irqthreads) {
 #ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
 		/*