x86/cpu/intel: Fix the MOVSL alignment preference for extended Families

The alignment preference for 32-bit MOVSL based bulk memory move has
been 8-byte for a long time. However this preference is only set for
Family 6 and 15 processors.

Use the same preference for upcoming Family numbers 18 and 19. Also, use
a simpler VFM based check instead of switching based on Family numbers.
Refresh the comment to reflect the new check.

Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250219184133.816753-3-sohil.mehta@intel.com