acpi/cstate: Set non-C3 state during generic Cx probing

Remove useless non-C3 state index setup in cx_list, which should
only reformat sysctl string.
acpi/cstate: Fix non-C3 setting

It should take lowest Cx setting into consideration.
acpi/cstate: Use u_long as stats type
acpi/cstate: Fix global Cx count setup