crypto: sha256_generic - Fix some coding style issues

Add a bunch of missing spaces after commas and arround operators.

Note the main goal of this is to make sha256_transform and its helpers
identical in formatting too the duplcate implementation in lib/sha256.c,
so that "diff -u" can be used to compare them to prove that no functional
changes are made when further patches in this series consolidate the 2
implementations into 1.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>