Trunk port FDMI supported port speed shows single port supported speed
rather than the trunked port speed.

Modify supported port speed logic calculation during registration.

Link: https://lore.kernel.org/r/20220412222008.126521-17-jsmart2021@gmail.comCo-developed-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>