Currently when the call to product_id_to_soc_id fails there
is a memory leak of soc_dev_attr->revision and soc_dev_attr
on the error return path.  Fix this by adding a common error
return path that frees there obects and use this for two
error return paths.

Addresses-Coverity: ("Resource leak")
Fixes: 3253b7b7 ("soc: samsung: Add exynos chipid driver support")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>