net: bcmgenet: Restore phy_stop() depending upon suspend/close

Removing the phy_stop() from bcmgenet_netif_stop() ended up causing
warnings from the PHY library that phy_start() is called from the
RUNNING state since we are no longer stopping the PHY state machine
during bcmgenet_suspend().

Restore the call to phy_stop() but make it conditional on being called
from the close or suspend path.

Fixes: c96e731c ("net: bcmgenet: connect and disconnect from the PHY state machine")
Fixes: 93e0401e

 ("net: bcmgenet: Remove phy_stop() from bcmgenet_netif_stop()")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Link: https://lore.kernel.org/r/20230515025608.2587012-1-f.fainelli@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>