x86/microcode: Announce reload operation's completion

By popular demand, issue a single line to dmesg after the reload
operation completes to let the user know that a reload has at least been
attempted.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190313110022.8229-1-bp@alien8.de