if_bnxt: Fix media speed update issue in "ifconfig -m" during PHY hot plug

Currently, if a media type (e.g., DAC) is hot-plugged out and another type
(e.g., optical cable) is hot-plugged in, the new speed is not reflected in
ifconfig. This occurs when the driver fails to update speeds with unchanged
tx and rx flow control.

To fix, a phy_type check ensures update of phy speeds upon detecting the new
phy.

Reviewed by: imp
Approved by: imp
Differential revision: https://reviews.freebsd.org/D42951