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

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.

Fixes: 8acacc40f733 ("net: ethernet: ti: am65-cpsw: Add minimal XDP support")
Reviewed-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Signed-off-by: Chintan Vankar <c-vankar@ti.com>
Link: https://patch.msgid.link/20250707085201.1898818-1-c-vankar@ti.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>