net: sh_eth: Disable WoL if system can not suspend

net: sh_eth: Disable WoL if system can not suspend

The MAC can't facilitate WoL if the system can't go to sleep. Gate the
WoL support callbacks in ethtool at compile time using CONFIG_PM_SLEEP.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20250909085849.3808169-1-niklas.soderlund+renesas@ragnatech.se
Signed-off-by: Jakub Kicinski <kuba@kernel.org>