x86: fix mpparse.c build error on latest git

Fix this by reintroducing asm/smp.h include in mpparse.c - later on
I will fix this by removing non-smp data from smp.h.

Reported-by: Petr Titera <P.Titera@century.cz>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>