arch/arm: Add necessary conversion between tick and usec in systick_interrupt

[blta]

fix tickless issue

Summary

• default tickless scheme with arm_systick.c don't works
• we add necessary conversion between tick and usec in systick_interrupt
• the local variable next_interval as the first parameter of low->callback , which unit is tick not usec,
  it seem that we must do conversion before and after calling

Impact

just fix tickless issue

Testing

We test this commit on our own platform:

hardware

• cpu ： cm55@armv8-m
• systick clk: 1M

config

CONFIG_ARMV8_SYSTICK=y
CONFIG_PER_TICK=1000
CONFIG_RR_INTERVAL=5
CONFIG_SCHED_TICKLESS=y
CONFIG_SYSTEM_TIMER64=y
CONFIG_TIMER_ARCH=y

test code

we add some testing code about delay in our chip's xxx_bring_up stage

syslog(LOG_INFO, "per_tick: %d\n", USER_PER_TICK);
syslog(LOG_INFO, "delay begin: %lu\n", clock_get_sched_ticks());
usleep(1000000);
syslog(LOG_INFO, "delay 1s: %lu\n", clock_get_sched_ticks());
usleep(5000000);
syslog(LOG_INFO, "delay 5s: %lu\n", clock_get_sched_ticks());
usleep(10000000);
syslog(LOG_INFO, "delay 10s: %lu\n", clock_get_sched_ticks());

test result

master branch

....
# can' t run these test code , no logs

add commit

[19:22:20.959]收←◆per tick: 1000
delay begin: 322

[19:22:21.956]收←◆delay 1s: 1323

[19:22:26.944]收←◆delay 5s: 6324

[19:22:36.919]收←◆delay 10s: 16325