x86/cpuidle: patch some indirect calls to direct ones

x86/cpuidle: patch some indirect calls to direct ones

For now only the ones used during entering/exiting of idle states are
converted. Additionally pm_idle{,_save} and lapic_timer_{on,off} can't
be converted, as they may get established rather late (when Dom0 is
already active).

Note that for patching to be deferred until after the pre-SMP initcalls
(from where cpuidle_init_cpu() runs the first time) the pointers need to
start out as NULL.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>