arch-x86: Add decoder syntax for fixed segment registers.

There is syntax for this already for fixed integer registers, which this
is patterned after. Rather than prefixing the operand descriptor with a
lower case "r", fixed segment registers are prefixed with a lower case
"s".

Change-Id: Ic08d323bef732a62de23f77ec805c8b7cd5e2303
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/55445
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
1 file changed