crypto: fcrypt - Remove 'do while(0)' loop for single statement macro

Remove the 'do while(0)' loop in the macro, as it is not needed for single
statement macros. Condense into one line.

Signed-off-by: Milan Djurovic <mdjurovic@zohomail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>