CONFIG_DEBUG_TEST_DRIVER_REMOVE needs a warning

[Laura Abbott]

On a whim, I decided to turn on CONFIG_DEBUG_TEST_DRIVER_REMOVE on
Fedora rawhide since it sounded harmless enough. It spewed warnings
and panicked some systems. Clearly it's  doing its job
well of finding drivers that can't handle remove properly and I
underestimated it. I was expecting to maybe find a driver or two.
Can we get stronger Kconfig text indicating that this shouldn't be
turned on lightly? I'll be turning the option off in Fedora but sending
out reports from what was found.

Thanks,
Laura