hwrng: cn10k - Make check_rng_health() return an error code

commit 2d25d3b7f83ae206379450f400521bee817e593d from
git@git.assembla.com:cavium/WindRiver.linux.git

Currently check_rng_health() returns zero unconditionally.
Make it to output an error code and return it.

Change-Id: If5e4fb2cf6340cf291694e8311fbe11905ed3d05
Fixes: 38e9791a ("hwrng: cn10k - Add random number generator support")
Signed-off-by: Vladis Dronov <vdronov@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Anil Kumar Reddy <areddy3@marvell.com>
Reviewed-on: https://sj1git1.cavium.com/c/IP/SW/kernel/linux/+/87096


Reviewed-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Tested-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: Ruiqiang Hao <Ruiqiang.Hao@windriver.com>