arch-x86: De-conditionalize segmentation microops.

These were never used with conditions, so the condition check just added
overhead. Also, the not-taken path through the instruction didn't
actually set the destination to something, meaning that it would set it
to something arbitrary and not actually leave it unmodified.

Change-Id: I33fef088979b14ad74adf22b26419a1cacf386dd
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/45305
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>

src/arch/x86/isa/microops/regop.isa

@@ -1400,7 +1400,7 @@ let {{
             '''
 
     # Microops for manipulating segmentation registers
-    class SegOp(CondRegOp):
+    class SegOp(RegOp):
         abstract = True
         operand_types = (SegDestOp, FoldedSrc1Op)
         def __init__(self, dest, src1, flags=None, dataSize="env.dataSize"):