net: stmmac: remove redundant fixup to support fixed-link mode

[ Upstream commit 6fc21a6e ]

Currently, intel_speed_mode_2500() will fix-up xpcs_an_inband
to 1 if the underlying controller has a max speed of 1000Mbps.
The value has been initialized and modified if it is
a fixed-linked setup earlier.

This patch removes the fix-up to allow for fixed-linked setup
support. In stmmac_phy_setup(), ovr_an_inband is set based on
the value of xpcs_an_inband. Which in turn will return an
error in phylink_parse_mode() where MLO_AN_FIXED and
ovr_an_inband are both set.

Fixes: c8238631 ("stmmac: intel: prepare to support 1000BASE-X phy interface setting")
Signed-off-by: Michael Sit Wei Hong <michael.wei.hong.sit@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>