bnxt: Add support for new phy_types and speeds - Part #2

Use our ifm_list of supported media types rather than nested switch
statements to find the current media type. Find a supported type that
matches the current speed.

Remove all workarounds while updating ifmr->ifm_active.

For BNXT_IFMEDIA_ADD, added Three more speeds IFM_10G_T, IFM_2500_T & IFM_2500_KX.

Submitted by: Bhargava Chenna Marreddy <bhargava.marreddy@broadcom.com>
Reviewed by: shurd, sbruno
Approved by: sbruno (mentor)
Sponsored by: Broadcom Limited
Differential Revision: https://reviews.freebsd.org/D12896