x86: I/O APIC: remove parameters to fiddle with the 8259A

Remove the "disable_8254_timer" and "enable_8254_timer" kernel
parameters.  Now that AEOI acknowledgements are no longer needed for
correct timer operation, the 8259A can be kept disabled unconditionally
unless interrupts, either timer or watchdog ones, are actually passed
through it.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>