Documentation: kernel-parameters.txt cleanups

General cleanups to kernel-parameters.txt:
 - add missing $ARCH that are being used/referenced
 - alphabetize the parameter restrictions list
 - spell "IA-64" as listed in arch/ia64/Kconfig instead of "IA64"
 - remove trailing whitespace
 - use hyphen in 32-bit etc.

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>