x86/mtrr: Add a stop_machine() handler calling only cache_cpu_init()

Instead of having a stop_machine() handler for either a specific
MTRR register or all state at once, add a handler just for calling
cache_cpu_init() if appropriate.

Add functions for calling stop_machine() with this handler as well.

Add a generic replacement for mtrr_bp_restore() and a wrapper for
mtrr_bp_init().

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20221102074713.21493-13-jgross@suse.com


Signed-off-by: Borislav Petkov <bp@suse.de>