X86: Add a delay between INIT & SIPIs for AP bring-up in X2APIC case

Without this delay, Xen could not bring APs up while working with TXT/tboot, because tboot need some time in APs to handle INIT before becoming ready for receiving SIPIs.

Signed-off-by: Gang Wei <gang.wei@intel.com>

diff -r d1aefee43af1 xen/arch/x86/smpboot.c
--- a/xen/arch/x86/smpboot.c    Wed Dec 21 18:51:31 2011 +0800
+++ b/xen/arch/x86/smpboot.c    Wed Dec 21 19:08:57 2011 +0800
@@ -463,6 +463,10 @@ static int wakeup_secondary_cpu(int phys
             send_status = apic_read(APIC_ICR) & APIC_ICR_BUSY;
         } while ( send_status && (timeout++ < 1000) );
     }
+    else
+    {
+        mdelay(10);
+    }

     /*
      * Should we send STARTUP IPIs ?