Merge branch 'stmmac-Clean-up-and-tune-up'

Jose Abreu says:

====================
net: stmmac: Clean-up and tune-up

This targets to uniformize the handling of the different GMAC versions in
stmmac_main.c file and also tune-up the HW.

Currently there are some if/else conditions in the main source file which
calls different callbacks depending on the ID of GMAC.

With the introducion of a generic HW interface handling which automatically
selects the GMAC callbacks to be used, it is now unpleasant to see if
conditions in the main code because this should be completely agnostic of the
GMAC version.

This series removes most of these conditions. There are some if conditions
that remain untouched but the callbacks handling are now uniformized.

Tested in GMAC5, hope I didn't break any previous versions.

Please check [1] for performance analisys of patches 3-12.
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Signed-off-by: David S. Miller <davem@davemloft.net>