[HVM][SVM] Allows 64bit HVM AMD-V Linux guests to boot.

Basically, this patch reverts part of c/s 12264.
Signed-off-by: Tom Woller <thomas.woller@amd.com>

xen/arch/x86/hvm/svm/svm.c

@@ -1526,10 +1526,9 @@ static int svm_set_cr0(unsigned long value)
 
         if (test_bit(SVM_CPU_STATE_LME_ENABLED, &v->arch.hvm_svm.cpu_state))
         {
-            /* Here the PAE is should to be opened */
             HVM_DBG_LOG(DBG_LEVEL_1, "Enable the Long mode\n");
             set_bit(SVM_CPU_STATE_LMA_ENABLED, &v->arch.hvm_svm.cpu_state);
-            vmcb->efer |= EFER_LMA;
+            vmcb->efer |= EFER_LMA | EFER_LME;
         }
 #endif  /* __x86_64__ */