ACPI: processor/idle: Annotate more functions to live in cpuidle section

Commit 6727ad9e ("nmi_backtrace: generate one-line reports for idle cpus")
introduced a new text section called cpuidle; with that, we have a mechanism
to add idling functions in such section and skip them from nmi_backtrace
output, since they're useless and potentially flooding for such report.

Happens that inlining might cause some real idle functions to end-up
outside of such section; this is currently the case of ACPI processor_idle
driver; the functions acpi_idle_enter_* do inline acpi_idle_do_entry(),
hence they stay out of the cpuidle section.
Fix that by marking such functions to also live in the cpuidle section.

Fixes: 6727ad9e ("nmi_backtrace: generate one-line reports for idle cpus")
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>