crypto: nx - rename nx-842-crypto.c to nx-842.c

The last commit merged nx-842.c's code into nx-842-crypto.c.  It
did not rename nx-842-crypto.c to nx-842.c, in order to let the
patch more clearly show what was merged.  This just renames
nx-842-crypto.c to nx-842.c, with no changes to its code.

Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>