x86: apic - unify smp_spurious/error_interrupt declaration

According to entry_64.S we do pass pt_regs pointer
into interrupt handlers but don't use them. So we
safely may merge the declarations.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>