c7c527dd6e
The removal of this file appears to have been premature; it's not a feature
enabled by Kconfig, but it's a arch-level feature regardless. Put it back
for now until some happy future time when we decide how we really want to
document such features.
This reverts commit 2bef69a385.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>