crypto: inside-secure - Minor code cleanup and optimizations

Some minor cleanup changing e.g. "if (!x) A else B" to "if (x) B else A",
merging some back-to-back if's with the same condition, collapsing some
back-to-back assignments to the same variable and replacing some weird
assignments with proper symbolics.

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