r8169: remove fiddling with the PCIe max read request size

r8169: remove fiddling with the PCIe max read request size

BugLink: https://bugs.launchpad.net/bugs/1926493
[ Upstream commit 2df49d36549808a7357ad9f78b7a8e39516e7809 ]

The attempt to improve performance by changing the PCIe max read request
size was added in the vendor driver more than 10 years back and copied
to r8169 driver. In the vendor driver this has been removed long ago.
Obviously it had no effect, also in my tests I didn't see any
difference. Typically the max payload size is less than 512 bytes
anyway, and the PCI core takes care that the maximum supported value
is set. So let's remove fiddling with PCIe max read request size from
r8169 too.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>