Revert "checkpatch: Error out if deprecated RCU API used"

The check for single-argument kfree_rcu() is no longer needed as all
users have been converted.

This reverts commit 1eacac3255495be7502d406e2ba5444fb5c3607c.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
1 file changed