crypto: doc - remove colons in comments

As documented in Documentation/kernel-doc-nano-HOWTO.txt lines
terminated with a colon are treated as headings.

The current layout of the documentation when compiling the kernel
crypto API DocBook documentation is messed up by by treating some lines
as headings. The patch removes colons from comments that shall not be
treated as headings.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>