net: stmmac: remove redundant WoL option validation

net: stmmac: remove redundant WoL option validation

The core ethtool API validates the WoL options passed from userspace
against the support which the driver reports from its get_wol() method,
returning EINVAL if an unsupported mode is requested.

Therefore, there is no need for stmmac to implement its own validation.
Remove this unnecessary code.

See ethnl_set_wol() in net/ethtool/wol.c and ethtool_set_wol() in
net/ethtool/ioctl.c.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1umsfA-008vKW-H1@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>