net: fec: manage ahb clock in runtime pm

net: fec: manage ahb clock in runtime pm

BugLink: https://bugs.launchpad.net/bugs/1838576
[ Upstream commit d7c3a206e6338e4ccdf030719dec028e26a521d5 ]

Some SOC like i.MX6SX clock have some limits:
- ahb clock should be disabled before ipg.
- ahb and ipg clocks are required for MAC MII bus.
So, move the ahb clock to runtime management together with
ipg clock.

Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>