x86/microcode: unify ucode loading during system bootup and resuming

x86/microcode: unify ucode loading during system bootup and resuming

During system bootup and resuming, CPUs just load the cached ucode.
So one unified function microcode_update_one() is introduced. It
takes a boolean to indicate whether ->start_update should be called.
Since early_microcode_update_cpu() is only called on BSP (APs call
the unified function), start_update is always true and so remove
this parameter.

There is a functional change: ->start_update is called on BSP and
->end_update_percpu is called during system resuming. They are not
invoked by previous microcode_resume_cpu().

Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>