x86/minios: remove more vestigial remnants of SUPERVISOR_MODE_KERNEL

MiniOS has never advertised support for supervisor_mode_kernel, and the
feature was only ever implemented for 32bit Xen.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

extras/mini-os/arch/x86/x86_64.S

@@ -125,13 +125,10 @@ KERNEL_CS_MASK = 0xfc
 	testl $NMI_MASK,2*8(%rsp)
 	jnz   2f
 
-	testb $1,(xen_features+XENFEAT_supervisor_mode_kernel)
-	jnz   1f
-
 	/* Direct iret to kernel space. Correct CS and SS. */
 	orb   $3,1*8(%rsp)
 	orb   $3,4*8(%rsp)
-1:	iretq
+	iretq
 
 2:	/* Slow iret via hypervisor. */
 	andl  $~NMI_MASK, 16(%rsp)