can: rockchip: rkcanfd_handle_rx_fifo_overflow_int(): bail out if skb cannot be allocated

In the Linux kernel, the following vulnerability has been resolved: can: rockchip: rkcanfd_handle_rx_fifo_overflow_int(): bail out if skb cannot be allocated Fix NULL pointer check in rkcanfd_handle_rx_fifo_overflow_int() to bail out if skb cannot be allocated.