crypto: ccree - simplify Runtime PM handling

Currently, a large part of the probe function runs before Runtime PM is
enabled.  As the driver manages the device's clock manually, this may
work fine on some systems, but may break on platforms with a more
complex power hierarchy.

Fix this by moving the initialization of Runtime PM before the first
register access (in cc_wait_for_reset_completion()), and putting the
device to sleep only after the last access (in cc_set_ree_fips_status()).

This allows to remove the pm_on flag, which was used to track manually
if Runtime PM had been enabled or not.
Remove the cc_pm_{init,go,fini}() wrappers, as they are called only
once, and obscure operation.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>