Change the IVB/HSW's max_work_group_size to 512, and BYT to 256.
Change the IVB/HSW's max_work_group_size to 512, and BYT to 256.

To decide the kernel's work group size, application should get
CL_DEVICE_MAX_WORK_GROUP_SIZE first, and then get the CL_KERNEL_WORK_GROUP_SIZE
after clBuildProgram.
But some application only check the CL_DEVICE_MAX_WORK_GROUP_SIZE, and if kernel run
simd8 mode or other cause, may exceed the CL_KERNEL_WORK_GROUP_SIZE.
So change to CL_DEVICE_MAX_WORK_GROUP_SIZE to the minimum CL_KERNEL_WORK_GROUP_SIZE.

Signed-off-by: Yang Rong <78759e37dc7114caed18f74e7515c5cb519dbf6d@intel.com>
Reviewed-by: Zhigang Gong <e04a7b9b70b1e4c6318cf117dcd1a9056e14b97a@linux.intel.com>

zhenyw/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,freedesktop-unofficial-mirror/beignet,zhenyw/beignet,zhenyw/beignet,wdv4758h/beignet,zhenyw/beignet,zhenyw/beignet,freedesktop-unofficial-mirror/beignet,freedesktop-unofficial-mirror/beignet,wdv4758h/beignet,freedesktop-unofficial-mirror/beignet