acpi: Use only AcpiGetSleepTypeData() to determine Sx support

[olce]

Summary

Previously, we would first call AcpiEvaluateObject() to execute \_Sx
before calling AcpiGetSleepTypeData(). This was unnecessary, as
AcpiGetSleepTypeData() performs the same call itself. While doing so,
the latter function logs any other error than AE_NOT_FOUND (which
indicates that a particular sleep state is not supported), which most
probably is an added benefit of this change.

[obiwac]

Tested on my machine (only S5, S4, and S0) and all works