Remapping the left key of tm2-touchkey to KEY_MENU.
The KEY_APPSELECT, which is set by the device tree, is not available in
the postmarketOS UIs. In X11 UIs this is due to keycode limitation to
8 bit. In Wayland UIs the keycodes don't have this limitation but xkb
keycodes higher 255 are not processed correctly by several software
packages. It still makes sense to keep KEY_APPSELECT in the device tree
because this is the correct mapping intended by the manufacturers when
running the kernel on Android.
