doc/kernel-parameters: use X86-32 tag instead of IA-32

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>