rtase: Implement a function to receive packets

Implement rx_handler to read the information of the rx descriptor,
thereby checking the packet accordingly and storing the packet
in the socket buffer to complete the reception of the packet.

Signed-off-by: Justin Lai <justinlai0215@realtek.com>
Link: https://patch.msgid.link/20240904032114.247117-8-justinlai0215@realtek.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>