bnxt: refactor bnxt_rx_pages operate on skb_shared_info

Rather than operating on an sk_buff, add frags from the aggregation
ring into the frags of an skb_shared_info.  This will allow the
caller to use either an sk_buff or xdp_buff.

Signed-off-by: Andy Gospodarek <gospo@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>