bnxt_re: Fix active_speed value when two ports are aggregated

Currently driver is not considering the active_lanes while
displaying the speed & width of port and hence it showing
invalid active_speed and active_width values in the ibv_devinfo
command output when two ports are aggregated at hardware level.
Fixed the driver to consider the active_lanes while determining
the active_speed & active_width values.

Reviewed by: ssaxena
Differential Revision: https://reviews.freebsd.org/D54523
MFC after: 3 days

(cherry picked from commit b7d6334df61a559e98191f90fd5e611e0d077def)