crypto: zstd - fix duplicate check warning

Fix the following warnings reported by the static analyzer Smatch:
    crypto/zstd.c:273 zstd_decompress()
    warn: duplicate check 'scur' (previous on line 235)

Fixes: f5ad93ff ("crypto: zstd - convert to acomp")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-crypto/92929e50-5650-40be-8c0a-de81e77f0acf@sabinyo.mountain/


Signed-off-by: Suman Kumar Chakraborty <suman.kumar.chakraborty@intel.com>
Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>