Pin 90 conflict on BeagleBone Enhanced.

A couple of years ago a pin was added to `davinci-mdio-default-pins` in `src/arm/ti/omap/am335x-bone-common.dtsi`, apparently for supporting a PHY reset signal via GPIO. The selected GPIO is GPIO1_8 (uart0_ctsn), which is unused on most BeagleBone variants, but is used on the BBE for an interrupt input from the Gyro chip. This leads to a pin conflict with the Gyro driver.

I wonder why a PHY reset pin was added to a file that is common for all BeagleBones based on the AM335x, when most variants don't use it! In my opinion, this pin setting ended up in the wrong file!

Start with src/arm/ti/omap/am335x-bone-common.dtsi and inspect the davinci-mdio-default-pins entry selecting GPIO1_8. Trace how that common pin setting affects BeagleBone Enhanced and its Gyro interrupt, then verify the PHY reset use across BeagleBone variants. Done means the BBE Gyro pin conflict is removed without breaking the relevant PHY reset configuration.

Written by the indexing model from the issue text.