fix ceil-div to avoid overflow (#370)
fix ceil-div to avoid overflow (#370)

* fix ceil-div when divisor is greater than UINT32_MAX

some platform have maxComputeWorkGroupCount equal to UINT_MAX.
It generates an overflow when computing num_splitted_regions in
cvk_command_kernel::dispatch_uniform_region_iterate

* avoid branch

* remove uneeded header

* use version allowing num == 0
kpet/clvk,kpet/clvk,kpet/clvk,kpet/clvk