crypto: omap-sham - increase cra_proirity to 400

The arm-neon-sha implementations have cra_priority of 150...300, so
increase omap-sham priority to 400 to ensure it is on top of any
software alg.

Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>