media: verisilicon: rockchip: guard VPU981 AV1 divisor and tile buffer

In the Linux kernel, the following vulnerability has been resolved: media: verisilicon: rockchip: guard VPU981 AV1 divisor and tile buffer rockchip_vpu981_av1_dec_set_tile_info() divides context_update_tile_id by tile_info->tile_cols and writes one descriptor per tile into the tile_info DMA buffer, which holds AV1_MAX_TILES entries; tile_cols and tile_rows come from the bitstream. Guard the division against a zero tile_cols by initialising the context-update values to zero and computing them only when tile_cols is non-zero, and stop the descriptor writes once the tile_info buffer is full. The tile geometry written to the hardware registers is left unmodified; the per-dimension and total tile bounds are enforced by the control validation.