Remove unnecessary TLB flushes

- this should be only for SMP

kernel/arch/i386/klib.S

@@ -803,7 +803,7 @@ ENTRY(__switch_address_space)
 	 * test if the cr3 is loaded with the current value to avoid unnecessary
 	 * TLB flushes
 	 */
-#if 0
+#ifndef CONFIG_SMP
 	mov	%cr3, %ecx
 	cmp	%ecx, %eax
 	je	0f

kernel/proc.c

@@ -374,7 +374,9 @@ check_misc_flags:
 	p->p_misc_flags &= ~MF_CONTEXT_SET;
 
   	assert(!(p->p_misc_flags & MF_FULLVM) || p->p_seg.p_cr3 != 0);
+#ifdef CONFIG_SMP
 	refresh_tlb();
+#endif
 	/*
 	 * restore_user_context() carries out the actual mode switch from kernel
 	 * to userspace. This function does not return