x86, mpparse: Put check_slot() into .init section

check_slot() is only called from replace_intsrc_all() - which is
in the .init section.

So, put check_slot into the .init section as well, so it can be freed
after system boot.
Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
LKML-Reference: <AANLkTing52ntzRcHkODCWDKOfRF=0uhXw5-cCUhx6M54@mail.gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/mpparse.c

@@ -715,7 +715,7 @@ static void __init check_irq_src(struct mpc_intsrc *m, int *nr_m_spare)
 	}
 }
 
-static int
+static int __init
 check_slot(unsigned long mpc_new_phys, unsigned long mpc_new_length, int count)
 {
 	int ret = 0;