libxl: Fix comment about dcs.sdss

The field 'sdss' was named 'dmss' before, commit 3148bebbf0 did the
renamed but didn't update the comment.

Fixes: 3148bebbf0 ("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 035c4d7716)
(cherry picked from commit 5351a0a170fc7f6290d7d3d8be302d53d2426a87)

tools/libxl/libxl_internal.h

@@ -4017,7 +4017,7 @@ struct libxl__domain_create_state {
     libxl__checkpoint_devices_state cds;
     libxl__bootloader_state bl;
     libxl__stub_dm_spawn_state sdss;
-        /* If we're not doing stubdom, we use only dmss.dm,
+        /* If we're not doing stubdom, we use only sdss.dm,
          * for the non-stubdom device model. */
     libxl__stream_read_state srs;
     /* necessary if the domain creation failed and we have to destroy it */