HSW: Workaround the slm address issue.

HSW: Workaround the slm address issue.

Each work group has it's own slm offset, and when dispatch threads,
TSG will handle it automatic in IVB. But it will fail in HSW.
After check, all work group's slm offset are 0, even the slm index is
correct in R0.0. So calc the slm offset for slm index, and add it
to the slm address.
TODO: need to find the root casue.

Signed-off-by: Yang Rong <rong.r.yang@intel.com>
Reviewed-by: Junyan He <junyan.he@inbox.com>