This reverts commit b5f5768a1f7a2c2d4b5ea63d03b7d11bd82f3d15.
Meanwhile it turned out that the following commit is the proper
workaround for the issue that b5f5768a1f7a tries to address. 8c6db38ed5d3 ("net: stmmac: work around sporadic tx issue on link-up")
It's nor clear why the to be reverted commit helped for one user,
for others it didn't make a difference.