powerpc/rfi-flush: Move out of HARDLOCKUP_DETECTOR #ifdef

The backport of the RFI flush support, done by me, has a minor bug in
that the code is inside an #ifdef CONFIG_HARDLOCKUP_DETECTOR, which is
incorrect.

This doesn't matter with common configs because we enable
HARDLOCKUP_DETECTOR, but with future patches it will break the build.
So fix it.

Fixes: c3b82ebe ("powerpc/64s: Add support for RFI flush of L1-D cache")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>