[rx51] ofono is unable to symlink gpios to /dev/cmt

Ofono currently tries to create a directory (/dev/cmt) and corresponding symlinks to modem gpios if they do not exist: https://git.kernel.org/pub/scm/network/ofono/ofono.git/tree/plugins/nokia-gpio.c#n660

This prevents the existing udev rule in the device-nokia-rx51 package from successfully creating a symlink. I could just call rmdir /dev/cmt in the udev rule before trying to symlink, but that seems hackish (and in my test, it didn't even work, but I have no idea why..)

It's currently looking for a name property that the gpio pins should have: http://elixir.free-electrons.com/linux/v4.13.3/source/arch/arm/boot/dts/omap3-n900.dts#L1039

However none of the gpios have a name file in their corresponding gpio device locations in sysfs, so ofono ultimately is unable to bring up the N900 modem.

@sre, any chance you have some ideas that could help? It seems like this did work at one point, else the nokia-gpio plugin in ofono would never have worked.

Maybe a better option is to have the nokia-modem driver (or whatever the correct module is) create and populate /dev/cmt/cm_*? It seems weird having ofono do this, and it seems weird requiring the user to symlink (e.g. with udev) /sys/bus/hsi/devices/n900-modem to /dev/cmt