keymap: Drop ThinkPad Yoga

keymap: Drop ThinkPad Yoga

The Yoga's firmware sends key events whenever it's being folded or unfolded.
These are thus *not* a button for requesting a screen orientation change, just
an indication that this already happened. Thus they should not be assigned to
"direction", but be ignored. Assigning them to "reserved" does not silence the
"unknown key pressed" kernel warning, so there's no point in maintaining a
mapping here.

Fixes #1440