x86/apic: Remove "disablelapic" cmdline option

The convention is "no<something>" and there already is "nolapic". Drop
the disable one.

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Link: https://lore.kernel.org/r/20241202190011.11979-2-bp@kernel.org