intel_idle: mark few variables as __read_mostly

JIRA: https://issues.redhat.com/browse/RHEL-11351



commit bd446829
Author: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Date:   Wed Apr 19 17:39:47 2023 +0300

    intel_idle: mark few variables as __read_mostly

    The intention is to clean up the code and make it look a bit more
    consistent.

    Mark all unitialized module parameter variables as __read_mostly,
    not just one of them. The other parameters are read-mostly too.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Signed-off-by: David Arcari <darcari@redhat.com>