net: stmmac: platform: legacy hooks for suspend()/resume() methods

net: stmmac: platform: legacy hooks for suspend()/resume() methods

Add legacy hooks for the suspend() and resume() methods to forward
these calls to the init() and exit() methods when the platform code
hasn't populated the two former methods. This allows us to get rid
of stmmac_pltfr_suspend() and stmmac_pltfr_resume().

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/E1ulXbh-008gql-LO@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>