crypto: inside-secure - Made .cra_priority value a define

Instead of having a fixed value (of 300) all over the place, the value for
for .cra_priority is now made into a define (SAFEXCEL_CRA_PRIORITY).
This makes it easier to play with, e.g. during development.

Signed-off-by: Pascal van Leeuwen <pvanleeuwen@verimatrix.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>