Runtime: fix the max group size for GT2.
Runtime: fix the max group size for GT2.

We should keep the max group size and the CL_KERNEL_WORK_GROUP_SIZE
consistency wit each other. Otherwise, the conformance test will trigger
an error.

Signed-off-by: Zhigang Gong <e04a7b9b70b1e4c6318cf117dcd1a9056e14b97a@linux.intel.com>
Reviewed-by: "Lu, Guanqun" <2dad72ae5fe48bf7bd43ddccece96ab3f4a6c25d@intel.com>

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