arch-power: Add word modulo instructions
arch-power: Add word modulo instructions

This adds the following instructions.
  * Modulo Signed Word (modsw)
  * Modulo Unsigned Word (moduw)

Change-Id: Id84ff46d0114ab859bd8616d3dcf22111cf3bda2
Signed-off-by: Sandipan Das <ae8113f64d9c72812e097938d25a8975da69c074@linux.ibm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/40909
Reviewed-by: Boris Shingarov <9e9a86074d235a5ecff50c3f2485c8b344969b31@labware.com>
Maintainer: Boris Shingarov <9e9a86074d235a5ecff50c3f2485c8b344969b31@labware.com>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>

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