net: stmmac: report EEE error statistics if EEE is supported

net: stmmac: report EEE error statistics if EEE is supported

Report the number of EEE error statistics in the xstats even when EEE
is not enabled in hardware, but is supported. The PHY maintains this
counter even when EEE is not enabled.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Choong Yong Liang <yong.liang.choong@linux.intel.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1tVZE6-0002KY-Nx@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>