crypto: omap-sham - drop old hw_init and unused FLAGS_INIT

FLAGS_INIT is now unused and we can just use standard runtime PM
functions instead.

Cc: Lokesh Vutla <lokeshvutla@ti.com>
Cc: Tero Kristo <kristo@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>