acpi/cstate: Function/variable/macro renaming

Adjust some comment.  No functional changes.
acpi/cstate: Save ACPI_GENERIC_ADDRESS for later use

Also fix a bug that 'res_type' should be used instead of 'type' during
FADT C state resource allocation.
acpi/cstate: Rearrange _CST reprobe code path
acpi/cstate: If there is bus master activity pick up non-C3 is enough

Since bus master activity is only checked before entering C3+ states.
acpi/cstate: Make sure that idle hook is installed as the last step
acpi/cstate: Add a method to per C-state softc to enter the C-state

This will be used to add "native" C-state support