crypto: drbg - make drbg_fips_continuous_test() return bool

crypto: drbg - make drbg_fips_continuous_test() return bool

Currently, drbg_fips_continuous_test() only returns 0 and -EAGAIN, so an
early return from the *do*/*while* loop in drbg_get_random_bytes() just
isn't possible. Make drbg_fips_continuous_test() return bool instead of
*int* (using true instead of 0 and false instead of -EAGAIN). This way,
we can further simplify drbg_get_random_bytes()...

Found by Linux Verification Center (linuxtesting.org) with the Svace static
analysis tool.

Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>