net: ti: icssg-prueth: introduce and use prueth_swdata struct for SWDATA

We have different cases for SWDATA (skb, page, cmd, etc)
so it is better to have a dedicated data structure for that.
We can embed the type field inside the struct and use it
to interpret the data in completion handlers.

Signed-off-by: Roger Quadros <rogerq@kernel.org>
Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
Signed-off-by: Meghana Malladi <m-malladi@ti.com>
Link: https://patch.msgid.link/20250305101422.1908370-3-m-malladi@ti.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>