Check to see if another kernel is installed, rather than asking the user

[robinpaulson]

After I do "ubuntu-mainline-kernel.sh -u" and select the kernel to uninstal, the script asks:

"Do you still have another kernel installed? (y/N)"

I'm sure we could check for another kernel installed, either from ubuntu-mainline-kernel.sh or from other (apt) sources. If there isn't a positive from either of those sources, then ask if there is another kernel installed.

Yes, it's minor, it's a small usability thing, not at all high priority.