ryu: update kernel prebuilt am: 212c37eb58
am: 941d8ab91d

Change-Id: I45278cb0fb5dc0ae9c5751c6da917fb6c169d895
tree: 2bfc6ab85ebaa93b23d923cb4e1dcc1e0e3f4ad4
  1. Image.fit
  2. Image.fit.kasan
  3. push-kernel.sh