net: stmmac: remove pcs_get_adv_lp() support

net: stmmac: remove pcs_get_adv_lp() support

It appears that the GMAC_ANE_ADV and GMAC_ANE_LPA registers are only
available for TBI and RTBI PHY interfaces. In commit 482b3c3ba757
("net: stmmac: Drop TBI/RTBI PCS flags") support for these was dropped,
and thus it no longer makes sense to access these registers.

Remove the *_get_adv_lp() functions, and the now redundant struct
rgmii_adv and STMMAC_PCS_* definitions.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/E1uPkbT-004EyG-OQ@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>