x86emul: use (locally) consistent exit mechanisms

At least similar code should use similar exit mechanisms (return vs
goto).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
RFC reason: There are many more paths where we could return directly,
            avoiding the _put_fpu() and put_stub(). Otoh arguably the
            two existing return-s around the changes below could also
            be changed to "goto done" to restore consistency.

Subsequently we may then want to consider to reduce the number of
"goto done" by checking rc right after at least the main switch()
statements.

--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -2112,7 +2112,7 @@ x86_emulate(
             op_bytes = 8;
         if ( (rc = ops->write(x86_seg_ss, sp_pre_dec(op_bytes),
                               &reg.sel, op_bytes, ctxt)) != 0 )
-            goto done;
+            return rc;
         break;
     }
 
@@ -2125,9 +2125,8 @@ x86_emulate(
         if ( mode_64bit() && (op_bytes == 4) )
             op_bytes = 8;
         if ( (rc = read_ulong(x86_seg_ss, sp_post_inc(op_bytes),
-                              &dst.val, op_bytes, ctxt, ops)) != 0 )
-            goto done;
-        if ( (rc = load_seg(src.val, dst.val, 0, NULL, ctxt, ops)) != 0 )
+                              &dst.val, op_bytes, ctxt, ops)) != 0 ||
+             (rc = load_seg(src.val, dst.val, 0, NULL, ctxt, ops)) != 0 )
             return rc;
         break;