x86/alternative: Remove unused header #defines

x86/alternative: Remove unused header #defines

Remove some unfortunately-named unused macros which could potentially
result in weird build failures. Fortunately, they are under an #ifdef
__ASSEMBLER__ which has kept them from causing problems so far.

[ dhansen: subject and changelog tweaks ]

Fixes: 1a6ade825079 ("x86/alternative: Convert the asm ALTERNATIVE_3() macro")
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20250505131646.29288-1-jgross%40suse.com