drm/panthor: Add vm_bind region with kbo range overlap check

In the Linux kernel, the following vulnerability has been resolved:

drm/panthor: Add vm_bind region with kbo range overlap check

When a VM is created, caller has to specify the range of the address space
carve-out set aside for mapping kernel BO's. That means vm_bind mappings of
UM-exposed BO's should not intersect with that region, but at the moment
we're not checking this.

At first, I thought of giving these values to drm_gpuvm_init() through its
reserve_{offset, range} arguments, but it turns out that is meant for VM
address spans that are not managed through the usual drm_gpuvm split/merge
circuit, so storing the end of the user VA range at VM creation time and
doing a quick check in the vm_bind ioctl path was the simplest workaround.

The new check also makes sure vm_bind range doesn't overflow the size of a
64-bit unsigned integer. That was already being done further down the call
stack inside drm_gpuvm_sm_map -> drm_gpuvm_range_valid, but it's best to
fail early in the driver before GPUVM functions are invoked so that we
won't waste time allocating vm_bind context resources.