fix: (docs) amdsmi_power_info_t->power_limit is really micro watts

[edman80]

This value is actually microwatts, so this updates the documentation.

You can see that even in amd-smi CLI tool, it is converted from SI_Unit.MICRO here

This value is populated into the amdsmi_power_info_t struct by reading powerX_cap out of the associated hwmon in sysfs. That can be seen here

Further, on an MI325X system, the card is certainly not capable of running at 1000000000 Watts:

root@linux:~# lspci | grep 06:00
06:00.0 Processing accelerators: Advanced Micro Devices, Inc. [AMD/ATI] Aqua Vanjaram [Instinct MI325X]
root@linux:~# cat /sys/bus/pci/devices/0000\:06\:00.0/hwmon/hwmon9/power1_cap
1000000000

From my testing, the other values in this struct, i.e current_socket_power do appear to return values in measures of Watts.