drivers: net: convert to boolean for the mac_managed_pm flag

[ Upstream commit eca485d2

 ]

Signed-off-by: Dennis Kirjanov <dkirjanov@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: cbc17e78

 ("net: fec: Set mac_managed_pm during probe")
Signed-off-by: Sasha Levin <sashal@kernel.org>