Merge branch 'net-stmmac-clean-up-descriptor-handling-part-1'

Russell King says:

====================
net: stmmac: clean up descriptor handling part 1

Part 1 of cleaning up the stmmac descriptor handling. Rearrange the
struct stmmac_tx_info to pack better, and introduce helpers for
duplicated code handing the transmit and receive descriptors. Remove
unnecessary struct members that are only transitorily used.
====================

Link: https://patch.msgid.link/abUtGH9KB03PH5Ne@shell.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>