libxl: Fix comment about dcs.sdss

libxl: Fix comment about dcs.sdss

The field 'sdss' was named 'dmss' before, commit 3148bebbf0ab did the
renamed but didn't update the comment.

Fixes: 3148bebbf0ab ("libxl: rename a field in libxl__domain_create_state")
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
(cherry picked from commit 035c4d771600f300382a1637f2da33023f76b4c1)
(cherry picked from commit 5351a0a170fc7f6290d7d3d8be302d53d2426a87)
(cherry picked from commit d1c9822b88463d91ca93fdc7e7fa6406efa7762f)