main: Run events at time intervals

[crawfxrd]

Rewrite the main loop to run all its events at certain intervals of the systick instead of running most on every loop.

• usbpd_event: Every 4 cycles -> 1ms
• power_event: Every 4 cycles -> 1ms
• kbscan_event: Every 4 cycles- > 5ms
• lid_event: Every 4 cycles -> 500ms
• board_event: Every cycle -> 1ms
• kbc_event: Every cycle -> 1ms
• pmc_event: Every cycle -> 1ms
• smfi_event: Every cycle -> 1ms
• battery_event: Every 1000ms

Ref: #209, Time-triggered architecture