crypto: omap-sham - Convert to use pm_runtime API

Convert the omap-sham crypto driver to use the
pm_runtime API instead of the clk API.

CC: Kevin Hilman <khilman@deeprootsystems.com>
CC: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>