net: ethernet: ti: am65-cpsw-nuss: Fix skb size by accounting for skb_shared_info

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

net: ethernet: ti: am65-cpsw-nuss: Fix skb size by accounting for skb_shared_info

While transitioning from netdev_alloc_ip_align() to build_skb(), memory for the "skb_shared_info" member of an "skb" was not allocated. Fix this by allocating "PAGE_SIZE" as the skb length, accounting for the packet length, headroom and tailroom, thereby including the required memory space for skb_shared_info.