x86/idt: Remove address argument from idt_invalidate()

There is no reason to specify any specific address to idt_invalidate(). It
looks mostly like an artifact of unifying code done differently by
accident. The most "sensible" address to set here is a NULL pointer -
virtual address zero, just as a visual marker.

This also makes it possible to mark the struct desc_ptr in idt_invalidate()
as static const.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210519212154.511983-5-hpa@zytor.com