CVE-2026-46312 media: videobuf2: Set vma_flags in vb2_dma_sg_mmap

In the Linux kernel, the following vulnerability has been resolved: media: videobuf2: Set vmaflags in vb2dmasgmmap vb2dmacontig sets VMA flags VMDONTEXPAND and VMDONTDUMP and I do not see a reason why vb2dmasg should behave differently. This avoids hitting WARNON!vma-vmflags & VMDONTEXPAND; in...