Fix stack assignment during CPU initialization

There are two errors in the code. The first one is a missing
$ sign in mov _stack, %esp. Thanks to Ronald G Minnich for
catching that bug.

The second bug is the 'incl %eax', which shouldn't be there, as
there's no secondary CPU with index 0. CPU0 uses always the stack
below _estack.

Change-Id: Id267a654ba95b0e898eeaaafb2403b438250a563
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-on: http://review.coreboot.org/1212
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/cpu/x86/lapic/secondary.S

@@ -53,10 +53,9 @@ __ap_protected_start:
 	movl	$1, %eax
 	lock	xadd %eax, cpucount
 	movl	%eax, %ecx
-	incl	%eax
 
 	/* assign stack for this specific cpu */
-	mov	_stack, %esp
+	mov	$_stack, %esp
 	mov	$CONFIG_STACK_SIZE, %ebx
 	mul	%ebx
 	add	%eax, %esp