net: phy: bcm54811: Fix GMII/MII/MII-Lite selection

net: phy: bcm54811: Fix GMII/MII/MII-Lite selection

The Broadcom bcm54811 is hardware-strapped to select among RGMII and
GMII/MII/MII-Lite modes. However, the corresponding bit, RGMII Enable
in Miscellaneous Control Register must be also set to select desired
RGMII or MII(-lite)/GMII mode.

Fixes: 3117a11fff5af9e7 ("net: phy: bcm54811: PHY initialization")
Signed-off-by: Kamil Horák - 2N <kamilh@axis.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://patch.msgid.link/20251009130656.1308237-2-kamilh@axis.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>