Get the passed in Bus/Device/Function from the correct location on the
stack.

Signed-off-by: Mark Marshall <mark.marshall@csr.com>

Index: util/x86emu/x86_asm.S
===================================================================
--- util/x86emu/x86_asm.S	(revision 4855)
+++ util/x86emu/x86_asm.S	(working copy)
@@ -68,8 +68,8 @@
 
 	/* Get devfn into %ecx */
 	movl    %esp, %ebp
-	// FIXME: Should this function be called with regparm=0?
-	movl    8(%ebp), %ecx
+	/* This function is now called with regparm=0. */
+	movl    36(%ebp), %ecx
 
 	/* Activate the right segment descriptor real mode. */
 	ljmp	$0x28, $RELOCATED(1f)