[SYCL] Expand coverage of reqd_work_group_size tests (intel#1457)

The reqd_work_group_size tests would previously only test for 3D kernels
which were known to be the only dimensionality of the attribute to work
as intended. Now that the attribute has been fixed we can extend this
testing.

Signed-off-by: Larsen, Steffen <[email protected]>

Author: steffenlarsen