amdsmu: Sleep entry/exit hints for PMFW

[obiwac_gmail.com]

Summary

amdsmu_enter and amdsmu_exit for sending hints to the AMD SMU power management firmware (PMFW) that we are entering and exiting sleep. We also dump sleep metrics once we tell it we're exiting sleep, so the relevant metrics are updated.

Added amdsmu_enter_sleep and amdsmu_exit_sleep device methods to the device interface for these functions. In the Do let me know if there's a better way to do one-off methods like this than adding them to device_if.m. I don't think this can just be on suspend and resume methods in any case, as I believe the AMD SMU exit hint must be called before the SPMC's exit hook and the entry hint must be called after the SPMC's entry.

acpi_EnterSleepState looks for the first device in the amdsmu devclass to call these entry/exit methods on.

Test Plan

I have tested this on the Framework 13 AMD Ryzen 7040 series (Phoenix):

% sysctl dev.amdsmu.0.metrics  
dev.amdsmu.0.metrics.total_time_in_sw_drips: 136191457
dev.amdsmu.0.metrics.time_last_in_sw_drips: 136191457
dev.amdsmu.0.metrics.total_time_in_s0i3: 0
dev.amdsmu.0.metrics.time_last_in_s0i3: 0
dev.amdsmu.0.metrics.total_time_resuming: 0
dev.amdsmu.0.metrics.time_last_resuming: 0
dev.amdsmu.0.metrics.total_time_entering_s0i3: 0
dev.amdsmu.0.metrics.time_last_entering_s0i3: 0
dev.amdsmu.0.metrics.time_last_in_s0i2: 0
dev.amdsmu.0.metrics.s0i3_last_entry_status: 0
dev.amdsmu.0.metrics.hint_count: 1
dev.amdsmu.0.metrics.table_version: 3

(Metrics after suspending-to-idle once for a little over 2 min.)