kernel: Remove undead ifdef CONFIG_DEBUG_LOCK_ALLOC

The CONFIG_DEBUG_LOCK_ALLOC ifdef isn't necessary at this point, because it is
checked in an outer ifdef level already and has no effect here.

Signed-off-by: Christian Dietrich <qy03fugy@stud.informatik.uni-erlangen.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>