RDMA/efa: Report link speed according to device attributes

RDMA/efa: Report link speed according to device attributes

Set port link speed and width based on max bandwidth acquired from the
device instead of using constant 100 Gbps. Use a default value in case
the device didn't set the field.

Reviewed-by: Daniel Kranzdorf <dkkranzd@amazon.com>
Reviewed-by: Firas Jahjah <firasj@amazon.com>
Signed-off-by: Michael Margolin <mrgolin@amazon.com>
Link: https://patch.msgid.link/20241030093006.21352-1-mrgolin@amazon.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>