The comment on BMCR data in if_media entry is wrong. The ifm_data stores
the index array, not a value for BMCR register. In case of IFM_10_T there
could be either MII_MEDIA_10_T or MII_MEDIA_10_T_FDX, which are 1 and 2,
accordingly. Neither matches a valid BMCR value. My guessing is that this
write is harmless, since later mii_phy_setmedia() would write a proper
value there.

The code is here since the initial checkin. Note that case IFM_100_TX has
the same comment, but a proper value of BMCR_ISO is written. So, collapse
two cases into one, always writing there BMCR_ISO.

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