Use broadcast SIPI to startup siblings

The current code for initializing AP cpus has several shortcomings:

- it assumes APIC IDs are sequential
- it uses only the BSP for determining the AP count, which is bad if
  there's more than one physical CPU, and CPUs are of different type

Note that the new code call cpu->ops->init() in parallel, and therefore
some CPU code needs to be changed to address that. One example are old
Intel HT enabled CPUs which can't do microcode update in parallel.

Change-Id: Ic48a1ebab6a7c52aa76765f497268af09fa38c25
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-on: http://review.coreboot.org/1139
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/cpu/intel/model_206ax/Kconfig

@@ -12,7 +12,6 @@ config CPU_SPECIFIC_OPTIONS
 	select SSE2
 	select UDELAY_LAPIC
 	select SMM_TSEG
-	#select AP_IN_SIPI_WAIT
 
 config BOOTBLOCK_CPU_INIT
 	string