net: mdio: mux-meson-gxl: set reversed bit when using internal phy

This bit is necessary to receive packets from the internal PHY.
Without this bit set, no activity occurs on the interface.

Normally u-boot sets this bit, but if u-boot is compiled without
net support, the interface will be up but without any activity.
If bit is set once, it will work until the IP is powered down or reset.

The vendor SDK sets this bit along with the PHY_ID bits.

Signed-off-by: Da Xue <da@libre.computer>
Fixes: 9a24e1ff ("net: mdio: add amlogic gxl mdio mux support")
Link: https://patch.msgid.link/20250425192009.1439508-1-da@libre.computer


Signed-off-by: Jakub Kicinski <kuba@kernel.org>