crypto: ccree - HOST_POWER_DOWN_EN should be the last CC access during suspend

During power management suspend the driver need to prepare the device
for the power down operation and as a last indication write to the
HOST_POWER_DOWN_EN register which signals to the hardware that
The ccree is ready for power down.

Signed-off-by: Ofir Drang <ofir.drang@arm.com>
Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>