drm/gpusvm: Reject VMAs with VM_IO or VM_PFNMAP when creating SVM ranges

In the Linux kernel, the following vulnerability has been resolved: drm/gpusvm: Reject VMAs with VM_IO or VM_PFNMAP when creating SVM ranges VMAs marked with VM_IO or VM_PFNMAP are not backed by struct page objects, which GPUSVM requires in order to operate correctly. In particular, get_pages() relies on hmm_range_fault() to resolve struct pages for the target range. Attempting to create an SVM range on such VMAs results in repeated get_pages() failures and can lead to an infinite loop inside a driver’s page‑fault handler. Prevent this by rejecting ranges on VM_IO or VM_PFNMAP VMAs and returning -EIO.