acpi_ibm: register all appropriate sysctls as uint

[Defenso-QTH]

All sysctls except thermal sensor readings and handlerevents whitelist-separated string are bitmasks or small integers. This avoids some bitmasks being erroneously displayed as negative values.

[github-actions]

Thank you for taking the time to contribute to FreeBSD!
All issues resolved.

[kprovost]

Should we also change acpi_ibm_sysctl()'s 'arg' variable to be unsigned?

[gmshake]

The function acpi_ibm_sysctl_get() which is called by acpi_ibm_sysctl() returns -1 in some cases. I think it needs more revising if change it to return unsigned int.