net: dsa: mt753x: remove ksz_get_mac_eee()

mt753x_get_mac_eee() is no longer called by the core DSA code. Remove
it.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Chester A. Unal <chester.a.unal@arinc9.com>
Link: https://patch.msgid.link/E1tUllF-007Uz3-95@rmk-PC.armlinux.org.uk


Signed-off-by: Jakub Kicinski <kuba@kernel.org>